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This is
/Volumes/Android/buildbot/src/android/ndk-release-r23/toolchain/make/doc/make.info,
produced by makeinfo version 4.8 from
/Volumes/Android/buildbot/src/android/ndk-release-r23/toolchain/make/doc/make.texi.
This file documents the GNU `make' utility, which determines
automatically which pieces of a large program need to be recompiled,
and issues the commands to recompile them.
This is Edition 0.75, last updated 21 May 2016, of `The GNU Make
Manual', for GNU `make' version 4.2.1.
Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996,
1997, 1998, 1999, 2000, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009,
2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020 Free
Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this
document under the terms of the GNU Free Documentation License,
Version 1.3 or any later version published by the Free Software
Foundation; with no Invariant Sections, with the Front-Cover Texts
being "A GNU Manual," and with the Back-Cover Texts as in (a)
below. A copy of the license is included in the section entitled
"GNU Free Documentation License."
(a) The FSF's Back-Cover Text is: "You have the freedom to copy and
modify this GNU manual. Buying copies from the FSF supports it in
developing GNU and promoting software freedom."
INFO-DIR-SECTION Software development
START-INFO-DIR-ENTRY
* Make: (make). Remake files automatically.
END-INFO-DIR-ENTRY

File: make.info, Node: Testing, Next: Options Summary, Prev: Overriding, Up: Running
9.6 Testing the Compilation of a Program
========================================
Normally, when an error happens in executing a shell command, `make'
gives up immediately, returning a nonzero status. No further recipes
are executed for any target. The error implies that the goal cannot be
correctly remade, and `make' reports this as soon as it knows.
When you are compiling a program that you have just changed, this is
not what you want. Instead, you would rather that `make' try compiling
every file that can be tried, to show you as many compilation errors as
possible.
On these occasions, you should use the `-k' or `--keep-going' flag.
This tells `make' to continue to consider the other prerequisites of
the pending targets, remaking them if necessary, before it gives up and
returns nonzero status. For example, after an error in compiling one
object file, `make -k' will continue compiling other object files even
though it already knows that linking them will be impossible. In
addition to continuing after failed shell commands, `make -k' will
continue as much as possible after discovering that it does not know
how to make a target or prerequisite file. This will always cause an
error message, but without `-k', it is a fatal error (*note Summary of
Options: Options Summary.).
The usual behavior of `make' assumes that your purpose is to get the
goals up to date; once `make' learns that this is impossible, it might
as well report the failure immediately. The `-k' flag says that the
real purpose is to test as much as possible of the changes made in the
program, perhaps to find several independent problems so that you can
correct them all before the next attempt to compile. This is why Emacs'
`M-x compile' command passes the `-k' flag by default.

File: make.info, Node: Options Summary, Prev: Testing, Up: Running
9.7 Summary of Options
======================
Here is a table of all the options `make' understands:
`-b'
`-m'
These options are ignored for compatibility with other versions of
`make'.
`-B'
`--always-make'
Consider all targets out-of-date. GNU `make' proceeds to consider
targets and their prerequisites using the normal algorithms;
however, all targets so considered are always remade regardless of
the status of their prerequisites. To avoid infinite recursion, if
`MAKE_RESTARTS' (*note Other Special Variables: Special
Variables.) is set to a number greater than 0 this option is
disabled when considering whether to remake makefiles (*note How
Makefiles Are Remade: Remaking Makefiles.).
`-C DIR'
`--directory=DIR'
Change to directory DIR before reading the makefiles. If multiple
`-C' options are specified, each is interpreted relative to the
previous one: `-C / -C etc' is equivalent to `-C /etc'. This is
typically used with recursive invocations of `make' (*note
Recursive Use of `make': Recursion.).
`-d'
Print debugging information in addition to normal processing. The
debugging information says which files are being considered for
remaking, which file-times are being compared and with what
results, which files actually need to be remade, which implicit
rules are considered and which are applied--everything interesting
about how `make' decides what to do. The `-d' option is
equivalent to `--debug=a' (see below).
`--debug[=OPTIONS]'
Print debugging information in addition to normal processing.
Various levels and types of output can be chosen. With no
arguments, print the "basic" level of debugging. Possible
arguments are below; only the first character is considered, and
values must be comma- or space-separated.
`a (all)'
All types of debugging output are enabled. This is
equivalent to using `-d'.
`b (basic)'
Basic debugging prints each target that was found to be
out-of-date, and whether the build was successful or not.
`v (verbose)'
A level above `basic'; includes messages about which
makefiles were parsed, prerequisites that did not need to be
rebuilt, etc. This option also enables `basic' messages.
`i (implicit)'
Prints messages describing the implicit rule searches for
each target. This option also enables `basic' messages.
`j (jobs)'
Prints messages giving details on the invocation of specific
sub-commands.
`m (makefile)'
By default, the above messages are not enabled while trying
to remake the makefiles. This option enables messages while
rebuilding makefiles, too. Note that the `all' option does
enable this option. This option also enables `basic'
messages.
`n (none)'
Disable all debugging currently enabled. If additional
debugging flags are encountered after this they will still
take effect.
`-e'
`--environment-overrides'
Give variables taken from the environment precedence over
variables from makefiles. *Note Variables from the Environment:
Environment.
`-E STRING'
`--eval=STRING'
Evaluate STRING as makefile syntax. This is a command-line
version of the `eval' function (*note Eval Function::). The
evaluation is performed after the default rules and variables have
been defined, but before any makefiles are read.
`-f FILE'
`--file=FILE'
`--makefile=FILE'
Read the file named FILE as a makefile. *Note Writing Makefiles:
Makefiles.
`-h'
`--help'
Remind you of the options that `make' understands and then exit.
`-i'
`--ignore-errors'
Ignore all errors in recipes executed to remake files. *Note
Errors in Recipes: Errors.
`-I DIR'
`--include-dir=DIR'
Specifies a directory DIR to search for included makefiles. *Note
Including Other Makefiles: Include. If several `-I' options are
used to specify several directories, the directories are searched
in the order specified.
`-j [JOBS]'
`--jobs[=JOBS]'
Specifies the number of recipes (jobs) to run simultaneously.
With no argument, `make' runs as many recipes simultaneously as
possible. If there is more than one `-j' option, the last one is
effective. *Note Parallel Execution: Parallel, for more
information on how recipes are run. Note that this option is
ignored on MS-DOS.
`-k'
`--keep-going'
Continue as much as possible after an error. While the target that
failed, and those that depend on it, cannot be remade, the other
prerequisites of these targets can be processed all the same.
*Note Testing the Compilation of a Program: Testing.
`-l [LOAD]'
`--load-average[=LOAD]'
`--max-load[=LOAD]'
Specifies that no new recipes should be started if there are other
recipes running and the load average is at least LOAD (a
floating-point number). With no argument, removes a previous load
limit. *Note Parallel Execution: Parallel.
`-L'
`--check-symlink-times'
On systems that support symbolic links, this option causes `make'
to consider the timestamps on any symbolic links in addition to the
timestamp on the file referenced by those links. When this option
is provided, the most recent timestamp among the file and the
symbolic links is taken as the modification time for this target
file.
`-n'
`--just-print'
`--dry-run'
`--recon'
Print the recipe that would be executed, but do not execute it
(except in certain circumstances). *Note Instead of Executing
Recipes: Instead of Execution.
`-o FILE'
`--old-file=FILE'
`--assume-old=FILE'
Do not remake the file FILE even if it is older than its
prerequisites, and do not remake anything on account of changes in
FILE. Essentially the file is treated as very old and its rules
are ignored. *Note Avoiding Recompilation of Some Files: Avoiding
Compilation.
`-O[TYPE]'
`--output-sync[=TYPE]'
Ensure that the complete output from each recipe is printed in one
uninterrupted sequence. This option is only useful when using the
`--jobs' option to run multiple recipes simultaneously (*note
Parallel Execution: Parallel.) Without this option output will be
displayed as it is generated by the recipes.
With no type or the type `target', output from the entire recipe
of each target is grouped together. With the type `line', output
from each line in the recipe is grouped together. With the type
`recurse', the output from an entire recursive make is grouped
together. With the type `none', no output synchronization is
performed. *Note Output During Parallel Execution: Parallel
Output.
`-p'
`--print-data-base'
Print the data base (rules and variable values) that results from
reading the makefiles; then execute as usual or as otherwise
specified. This also prints the version information given by the
`-v' switch (see below). To print the data base without trying to
remake any files, use `make -qp'. To print the data base of
predefined rules and variables, use `make -p -f /dev/null'. The
data base output contains file name and line number information for
recipe and variable definitions, so it can be a useful debugging
tool in complex environments.
`-q'
`--question'
"Question mode". Do not run any recipes, or print anything; just
return an exit status that is zero if the specified targets are
already up to date, one if any remaking is required, or two if an
error is encountered. *Note Instead of Executing Recipes: Instead
of Execution.
`-r'
`--no-builtin-rules'
Eliminate use of the built-in implicit rules (*note Using Implicit
Rules: Implicit Rules.). You can still define your own by writing
pattern rules (*note Defining and Redefining Pattern Rules:
Pattern Rules.). The `-r' option also clears out the default list
of suffixes for suffix rules (*note Old-Fashioned Suffix Rules:
Suffix Rules.). But you can still define your own suffixes with a
rule for `.SUFFIXES', and then define your own suffix rules. Note
that only _rules_ are affected by the `-r' option; default
variables remain in effect (*note Variables Used by Implicit
Rules: Implicit Variables.); see the `-R' option below.
`-R'
`--no-builtin-variables'
Eliminate use of the built-in rule-specific variables (*note
Variables Used by Implicit Rules: Implicit Variables.). You can
still define your own, of course. The `-R' option also
automatically enables the `-r' option (see above), since it
doesn't make sense to have implicit rules without any definitions
for the variables that they use.
`-s'
`--silent'
`--quiet'
Silent operation; do not print the recipes as they are executed.
*Note Recipe Echoing: Echoing.
`-S'
`--no-keep-going'
`--stop'
Cancel the effect of the `-k' option. This is never necessary
except in a recursive `make' where `-k' might be inherited from
the top-level `make' via `MAKEFLAGS' (*note Recursive Use of
`make': Recursion.) or if you set `-k' in `MAKEFLAGS' in your
environment.
`-t'
`--touch'
Touch files (mark them up to date without really changing them)
instead of running their recipes. This is used to pretend that the
recipes were done, in order to fool future invocations of `make'.
*Note Instead of Executing Recipes: Instead of Execution.
`--trace'
Show tracing information for `make' execution. Prints the entire
recipe to be executed, even for recipes that are normally silent
(due to `.SILENT' or `@'). Also prints the makefile name and line
number where the recipe was defined, and information on why the
target is being rebuilt.
`-v'
`--version'
Print the version of the `make' program plus a copyright, a list
of authors, and a notice that there is no warranty; then exit.
`-w'
`--print-directory'
Print a message containing the working directory both before and
after executing the makefile. This may be useful for tracking
down errors from complicated nests of recursive `make' commands.
*Note Recursive Use of `make': Recursion. (In practice, you
rarely need to specify this option since `make' does it for you;
see *Note The `--print-directory' Option: -w Option.)
`--no-print-directory'
Disable printing of the working directory under `-w'. This option
is useful when `-w' is turned on automatically, but you do not
want to see the extra messages. *Note The `--print-directory'
Option: -w Option.
`-W FILE'
`--what-if=FILE'
`--new-file=FILE'
`--assume-new=FILE'
Pretend that the target FILE has just been modified. When used
with the `-n' flag, this shows you what would happen if you were
to modify that file. Without `-n', it is almost the same as
running a `touch' command on the given file before running `make',
except that the modification time is changed only in the
imagination of `make'. *Note Instead of Executing Recipes:
Instead of Execution.
`--warn-undefined-variables'
Issue a warning message whenever `make' sees a reference to an
undefined variable. This can be helpful when you are trying to
debug makefiles which use variables in complex ways.

File: make.info, Node: Implicit Rules, Next: Archives, Prev: Running, Up: Top
10 Using Implicit Rules
***********************
Certain standard ways of remaking target files are used very often. For
example, one customary way to make an object file is from a C source
file using the C compiler, `cc'.
"Implicit rules" tell `make' how to use customary techniques so that
you do not have to specify them in detail when you want to use them.
For example, there is an implicit rule for C compilation. File names
determine which implicit rules are run. For example, C compilation
typically takes a `.c' file and makes a `.o' file. So `make' applies
the implicit rule for C compilation when it sees this combination of
file name endings.
A chain of implicit rules can apply in sequence; for example, `make'
will remake a `.o' file from a `.y' file by way of a `.c' file.
The built-in implicit rules use several variables in their recipes so
that, by changing the values of the variables, you can change the way
the implicit rule works. For example, the variable `CFLAGS' controls
the flags given to the C compiler by the implicit rule for C
compilation.
You can define your own implicit rules by writing "pattern rules".
"Suffix rules" are a more limited way to define implicit rules.
Pattern rules are more general and clearer, but suffix rules are
retained for compatibility.
* Menu:
* Using Implicit:: How to use an existing implicit rule
to get the recipes for updating a file.
* Catalogue of Rules:: A list of built-in rules.
* Implicit Variables:: How to change what predefined rules do.
* Chained Rules:: How to use a chain of implicit rules.
* Pattern Rules:: How to define new implicit rules.
* Last Resort:: How to define a recipe for rules which
cannot find any.
* Suffix Rules:: The old-fashioned style of implicit rule.
* Implicit Rule Search:: The precise algorithm for applying
implicit rules.

File: make.info, Node: Using Implicit, Next: Catalogue of Rules, Prev: Implicit Rules, Up: Implicit Rules
10.1 Using Implicit Rules
=========================
To allow `make' to find a customary method for updating a target file,
all you have to do is refrain from specifying recipes yourself. Either
write a rule with no recipe, or don't write a rule at all. Then `make'
will figure out which implicit rule to use based on which kind of
source file exists or can be made.
For example, suppose the makefile looks like this:
foo : foo.o bar.o
cc -o foo foo.o bar.o $(CFLAGS) $(LDFLAGS)
Because you mention `foo.o' but do not give a rule for it, `make' will
automatically look for an implicit rule that tells how to update it.
This happens whether or not the file `foo.o' currently exists.
If an implicit rule is found, it can supply both a recipe and one or
more prerequisites (the source files). You would want to write a rule
for `foo.o' with no recipe if you need to specify additional
prerequisites, such as header files, that the implicit rule cannot
supply.
Each implicit rule has a target pattern and prerequisite patterns.
There may be many implicit rules with the same target pattern. For
example, numerous rules make `.o' files: one, from a `.c' file with the
C compiler; another, from a `.p' file with the Pascal compiler; and so
on. The rule that actually applies is the one whose prerequisites
exist or can be made. So, if you have a file `foo.c', `make' will run
the C compiler; otherwise, if you have a file `foo.p', `make' will run
the Pascal compiler; and so on.
Of course, when you write the makefile, you know which implicit rule
you want `make' to use, and you know it will choose that one because you
know which possible prerequisite files are supposed to exist. *Note
Catalogue of Built-In Rules: Catalogue of Rules, for a catalogue of all
the predefined implicit rules.
Above, we said an implicit rule applies if the required
prerequisites "exist or can be made". A file "can be made" if it is
mentioned explicitly in the makefile as a target or a prerequisite, or
if an implicit rule can be recursively found for how to make it. When
an implicit prerequisite is the result of another implicit rule, we say
that "chaining" is occurring. *Note Chains of Implicit Rules: Chained
Rules.
In general, `make' searches for an implicit rule for each target, and
for each double-colon rule, that has no recipe. A file that is
mentioned only as a prerequisite is considered a target whose rule
specifies nothing, so implicit rule search happens for it. *Note
Implicit Rule Search Algorithm: Implicit Rule Search, for the details
of how the search is done.
Note that explicit prerequisites do not influence implicit rule
search. For example, consider this explicit rule:
foo.o: foo.p
The prerequisite on `foo.p' does not necessarily mean that `make' will
remake `foo.o' according to the implicit rule to make an object file, a
`.o' file, from a Pascal source file, a `.p' file. For example, if
`foo.c' also exists, the implicit rule to make an object file from a C
source file is used instead, because it appears before the Pascal rule
in the list of predefined implicit rules (*note Catalogue of Built-In
Rules: Catalogue of Rules.).
If you do not want an implicit rule to be used for a target that has
no recipe, you can give that target an empty recipe by writing a
semicolon (*note Defining Empty Recipes: Empty Recipes.).

File: make.info, Node: Catalogue of Rules, Next: Implicit Variables, Prev: Using Implicit, Up: Implicit Rules
10.2 Catalogue of Built-In Rules
================================
Here is a catalogue of predefined implicit rules which are always
available unless the makefile explicitly overrides or cancels them.
*Note Canceling Implicit Rules: Canceling Rules, for information on
canceling or overriding an implicit rule. The `-r' or
`--no-builtin-rules' option cancels all predefined rules.
This manual only documents the default rules available on POSIX-based
operating systems. Other operating systems, such as VMS, Windows,
OS/2, etc. may have different sets of default rules. To see the full
list of default rules and variables available in your version of GNU
`make', run `make -p' in a directory with no makefile.
Not all of these rules will always be defined, even when the `-r'
option is not given. Many of the predefined implicit rules are
implemented in `make' as suffix rules, so which ones will be defined
depends on the "suffix list" (the list of prerequisites of the special
target `.SUFFIXES'). The default suffix list is: `.out', `.a', `.ln',
`.o', `.c', `.cc', `.C', `.cpp', `.p', `.f', `.F', `.m', `.r', `.y',
`.l', `.ym', `.lm', `.s', `.S', `.mod', `.sym', `.def', `.h', `.info',
`.dvi', `.tex', `.texinfo', `.texi', `.txinfo', `.w', `.ch' `.web',
`.sh', `.elc', `.el'. All of the implicit rules described below whose
prerequisites have one of these suffixes are actually suffix rules. If
you modify the suffix list, the only predefined suffix rules in effect
will be those named by one or two of the suffixes that are on the list
you specify; rules whose suffixes fail to be on the list are disabled.
*Note Old-Fashioned Suffix Rules: Suffix Rules, for full details on
suffix rules.
Compiling C programs
`N.o' is made automatically from `N.c' with a recipe of the form
`$(CC) $(CPPFLAGS) $(CFLAGS) -c'.
Compiling C++ programs
`N.o' is made automatically from `N.cc', `N.cpp', or `N.C' with a
recipe of the form `$(CXX) $(CPPFLAGS) $(CXXFLAGS) -c'. We
encourage you to use the suffix `.cc' for C++ source files instead
of `.C'.
Compiling Pascal programs
`N.o' is made automatically from `N.p' with the recipe `$(PC)
$(PFLAGS) -c'.
Compiling Fortran and Ratfor programs
`N.o' is made automatically from `N.r', `N.F' or `N.f' by running
the Fortran compiler. The precise recipe used is as follows:
`.f'
`$(FC) $(FFLAGS) -c'.
`.F'
`$(FC) $(FFLAGS) $(CPPFLAGS) -c'.
`.r'
`$(FC) $(FFLAGS) $(RFLAGS) -c'.
Preprocessing Fortran and Ratfor programs
`N.f' is made automatically from `N.r' or `N.F'. This rule runs
just the preprocessor to convert a Ratfor or preprocessable
Fortran program into a strict Fortran program. The precise recipe
used is as follows:
`.F'
`$(FC) $(CPPFLAGS) $(FFLAGS) -F'.
`.r'
`$(FC) $(FFLAGS) $(RFLAGS) -F'.
Compiling Modula-2 programs
`N.sym' is made from `N.def' with a recipe of the form `$(M2C)
$(M2FLAGS) $(DEFFLAGS)'. `N.o' is made from `N.mod'; the form is:
`$(M2C) $(M2FLAGS) $(MODFLAGS)'.
Assembling and preprocessing assembler programs
`N.o' is made automatically from `N.s' by running the assembler,
`as'. The precise recipe is `$(AS) $(ASFLAGS)'.
`N.s' is made automatically from `N.S' by running the C
preprocessor, `cpp'. The precise recipe is `$(CPP) $(CPPFLAGS)'.
Linking a single object file
`N' is made automatically from `N.o' by running the linker
(usually called `ld') via the C compiler. The precise recipe used
is `$(CC) $(LDFLAGS) N.o $(LOADLIBES) $(LDLIBS)'.
This rule does the right thing for a simple program with only one
source file. It will also do the right thing if there are multiple
object files (presumably coming from various other source files),
one of which has a name matching that of the executable file.
Thus,
x: y.o z.o
when `x.c', `y.c' and `z.c' all exist will execute:
cc -c x.c -o x.o
cc -c y.c -o y.o
cc -c z.c -o z.o
cc x.o y.o z.o -o x
rm -f x.o
rm -f y.o
rm -f z.o
In more complicated cases, such as when there is no object file
whose name derives from the executable file name, you must write
an explicit recipe for linking.
Each kind of file automatically made into `.o' object files will
be automatically linked by using the compiler (`$(CC)', `$(FC)' or
`$(PC)'; the C compiler `$(CC)' is used to assemble `.s' files)
without the `-c' option. This could be done by using the `.o'
object files as intermediates, but it is faster to do the
compiling and linking in one step, so that's how it's done.
Yacc for C programs
`N.c' is made automatically from `N.y' by running Yacc with the
recipe `$(YACC) $(YFLAGS)'.
Lex for C programs
`N.c' is made automatically from `N.l' by running Lex. The actual
recipe is `$(LEX) $(LFLAGS)'.
Lex for Ratfor programs
`N.r' is made automatically from `N.l' by running Lex. The actual
recipe is `$(LEX) $(LFLAGS)'.
The convention of using the same suffix `.l' for all Lex files
regardless of whether they produce C code or Ratfor code makes it
impossible for `make' to determine automatically which of the two
languages you are using in any particular case. If `make' is
called upon to remake an object file from a `.l' file, it must
guess which compiler to use. It will guess the C compiler, because
that is more common. If you are using Ratfor, make sure `make'
knows this by mentioning `N.r' in the makefile. Or, if you are
using Ratfor exclusively, with no C files, remove `.c' from the
list of implicit rule suffixes with:
.SUFFIXES:
.SUFFIXES: .o .r .f .l ...
Making Lint Libraries from C, Yacc, or Lex programs
`N.ln' is made from `N.c' by running `lint'. The precise recipe
is `$(LINT) $(LINTFLAGS) $(CPPFLAGS) -i'. The same recipe is used
on the C code produced from `N.y' or `N.l'.
TeX and Web
`N.dvi' is made from `N.tex' with the recipe `$(TEX)'. `N.tex' is
made from `N.web' with `$(WEAVE)', or from `N.w' (and from `N.ch'
if it exists or can be made) with `$(CWEAVE)'. `N.p' is made from
`N.web' with `$(TANGLE)' and `N.c' is made from `N.w' (and from
`N.ch' if it exists or can be made) with `$(CTANGLE)'.
Texinfo and Info
`N.dvi' is made from `N.texinfo', `N.texi', or `N.txinfo', with
the recipe `$(TEXI2DVI) $(TEXI2DVI_FLAGS)'. `N.info' is made from
`N.texinfo', `N.texi', or `N.txinfo', with the recipe
`$(MAKEINFO) $(MAKEINFO_FLAGS)'.
RCS
Any file `N' is extracted if necessary from an RCS file named
either `N,v' or `RCS/N,v'. The precise recipe used is
`$(CO) $(COFLAGS)'. `N' will not be extracted from RCS if it
already exists, even if the RCS file is newer. The rules for RCS
are terminal (*note Match-Anything Pattern Rules: Match-Anything
Rules.), so RCS files cannot be generated from another source;
they must actually exist.
SCCS
Any file `N' is extracted if necessary from an SCCS file named
either `s.N' or `SCCS/s.N'. The precise recipe used is
`$(GET) $(GFLAGS)'. The rules for SCCS are terminal (*note
Match-Anything Pattern Rules: Match-Anything Rules.), so SCCS
files cannot be generated from another source; they must actually
exist.
For the benefit of SCCS, a file `N' is copied from `N.sh' and made
executable (by everyone). This is for shell scripts that are
checked into SCCS. Since RCS preserves the execution permission
of a file, you do not need to use this feature with RCS.
We recommend that you avoid using of SCCS. RCS is widely held to
be superior, and is also free. By choosing free software in place
of comparable (or inferior) proprietary software, you support the
free software movement.
Usually, you want to change only the variables listed in the table
above, which are documented in the following section.
However, the recipes in built-in implicit rules actually use
variables such as `COMPILE.c', `LINK.p', and `PREPROCESS.S', whose
values contain the recipes listed above.
`make' follows the convention that the rule to compile a `.X' source
file uses the variable `COMPILE.X'. Similarly, the rule to produce an
executable from a `.X' file uses `LINK.X'; and the rule to preprocess a
`.X' file uses `PREPROCESS.X'.
Every rule that produces an object file uses the variable
`OUTPUT_OPTION'. `make' defines this variable either to contain `-o
$@', or to be empty, depending on a compile-time option. You need the
`-o' option to ensure that the output goes into the right file when the
source file is in a different directory, as when using `VPATH' (*note
Directory Search::). However, compilers on some systems do not accept
a `-o' switch for object files. If you use such a system, and use
`VPATH', some compilations will put their output in the wrong place. A
possible workaround for this problem is to give `OUTPUT_OPTION' the
value `; mv $*.o $@'.

File: make.info, Node: Implicit Variables, Next: Chained Rules, Prev: Catalogue of Rules, Up: Implicit Rules
10.3 Variables Used by Implicit Rules
=====================================
The recipes in built-in implicit rules make liberal use of certain
predefined variables. You can alter the values of these variables in
the makefile, with arguments to `make', or in the environment to alter
how the implicit rules work without redefining the rules themselves.
You can cancel all variables used by implicit rules with the `-R' or
`--no-builtin-variables' option.
For example, the recipe used to compile a C source file actually says
`$(CC) -c $(CFLAGS) $(CPPFLAGS)'. The default values of the variables
used are `cc' and nothing, resulting in the command `cc -c'. By
redefining `CC' to `ncc', you could cause `ncc' to be used for all C
compilations performed by the implicit rule. By redefining `CFLAGS' to
be `-g', you could pass the `-g' option to each compilation. _All_
implicit rules that do C compilation use `$(CC)' to get the program
name for the compiler and _all_ include `$(CFLAGS)' among the arguments
given to the compiler.
The variables used in implicit rules fall into two classes: those
that are names of programs (like `CC') and those that contain arguments
for the programs (like `CFLAGS'). (The "name of a program" may also
contain some command arguments, but it must start with an actual
executable program name.) If a variable value contains more than one
argument, separate them with spaces.
The following tables describe of some of the more commonly-used
predefined variables. This list is not exhaustive, and the default
values shown here may not be what `make' selects for your environment.
To see the complete list of predefined variables for your instance of
GNU `make' you can run `make -p' in a directory with no makefiles.
Here is a table of some of the more common variables used as names of
programs in built-in rules:
`AR'
Archive-maintaining program; default `ar'.
`AS'
Program for compiling assembly files; default `as'.
`CC'
Program for compiling C programs; default `cc'.
`CXX'
Program for compiling C++ programs; default `g++'.
`CPP'
Program for running the C preprocessor, with results to standard
output; default `$(CC) -E'.
`FC'
Program for compiling or preprocessing Fortran and Ratfor programs;
default `f77'.
`M2C'
Program to use to compile Modula-2 source code; default `m2c'.
`PC'
Program for compiling Pascal programs; default `pc'.
`CO'
Program for extracting a file from RCS; default `co'.
`GET'
Program for extracting a file from SCCS; default `get'.
`LEX'
Program to use to turn Lex grammars into source code; default
`lex'.
`YACC'
Program to use to turn Yacc grammars into source code; default
`yacc'.
`LINT'
Program to use to run lint on source code; default `lint'.
`MAKEINFO'
Program to convert a Texinfo source file into an Info file; default
`makeinfo'.
`TEX'
Program to make TeX DVI files from TeX source; default `tex'.
`TEXI2DVI'
Program to make TeX DVI files from Texinfo source; default
`texi2dvi'.
`WEAVE'
Program to translate Web into TeX; default `weave'.
`CWEAVE'
Program to translate C Web into TeX; default `cweave'.
`TANGLE'
Program to translate Web into Pascal; default `tangle'.
`CTANGLE'
Program to translate C Web into C; default `ctangle'.
`RM'
Command to remove a file; default `rm -f'.
Here is a table of variables whose values are additional arguments
for the programs above. The default values for all of these is the
empty string, unless otherwise noted.
`ARFLAGS'
Flags to give the archive-maintaining program; default `rv'.
`ASFLAGS'
Extra flags to give to the assembler (when explicitly invoked on a
`.s' or `.S' file).
`CFLAGS'
Extra flags to give to the C compiler.
`CXXFLAGS'
Extra flags to give to the C++ compiler.
`COFLAGS'
Extra flags to give to the RCS `co' program.
`CPPFLAGS'
Extra flags to give to the C preprocessor and programs that use it
(the C and Fortran compilers).
`FFLAGS'
Extra flags to give to the Fortran compiler.
`GFLAGS'
Extra flags to give to the SCCS `get' program.
`LDFLAGS'
Extra flags to give to compilers when they are supposed to invoke
the linker, `ld', such as `-L'. Libraries (`-lfoo') should be
added to the `LDLIBS' variable instead.
`LDLIBS'
Library flags or names given to compilers when they are supposed to
invoke the linker, `ld'. `LOADLIBES' is a deprecated (but still
supported) alternative to `LDLIBS'. Non-library linker flags,
such as `-L', should go in the `LDFLAGS' variable.
`LFLAGS'
Extra flags to give to Lex.
`YFLAGS'
Extra flags to give to Yacc.
`PFLAGS'
Extra flags to give to the Pascal compiler.
`RFLAGS'
Extra flags to give to the Fortran compiler for Ratfor programs.
`LINTFLAGS'
Extra flags to give to lint.

File: make.info, Node: Chained Rules, Next: Pattern Rules, Prev: Implicit Variables, Up: Implicit Rules
10.4 Chains of Implicit Rules
=============================
Sometimes a file can be made by a sequence of implicit rules. For
example, a file `N.o' could be made from `N.y' by running first Yacc
and then `cc'. Such a sequence is called a "chain".
If the file `N.c' exists, or is mentioned in the makefile, no
special searching is required: `make' finds that the object file can be
made by C compilation from `N.c'; later on, when considering how to
make `N.c', the rule for running Yacc is used. Ultimately both `N.c'
and `N.o' are updated.
However, even if `N.c' does not exist and is not mentioned, `make'
knows how to envision it as the missing link between `N.o' and `N.y'!
In this case, `N.c' is called an "intermediate file". Once `make' has
decided to use the intermediate file, it is entered in the data base as
if it had been mentioned in the makefile, along with the implicit rule
that says how to create it.
Intermediate files are remade using their rules just like all other
files. But intermediate files are treated differently in two ways.
The first difference is what happens if the intermediate file does
not exist. If an ordinary file B does not exist, and `make' considers
a target that depends on B, it invariably creates B and then updates
the target from B. But if B is an intermediate file, then `make' can
leave well enough alone. It won't bother updating B, or the ultimate
target, unless some prerequisite of B is newer than that target or
there is some other reason to update that target.
The second difference is that if `make' _does_ create B in order to
update something else, it deletes B later on after it is no longer
needed. Therefore, an intermediate file which did not exist before
`make' also does not exist after `make'. `make' reports the deletion
to you by printing a `rm -f' command showing which file it is deleting.
Ordinarily, a file cannot be intermediate if it is mentioned in the
makefile as a target or prerequisite. However, you can explicitly mark
a file as intermediate by listing it as a prerequisite of the special
target `.INTERMEDIATE'. This takes effect even if the file is mentioned
explicitly in some other way.
You can prevent automatic deletion of an intermediate file by
marking it as a "secondary" file. To do this, list it as a
prerequisite of the special target `.SECONDARY'. When a file is
secondary, `make' will not create the file merely because it does not
already exist, but `make' does not automatically delete the file.
Marking a file as secondary also marks it as intermediate.
You can list the target pattern of an implicit rule (such as `%.o')
as a prerequisite of the special target `.PRECIOUS' to preserve
intermediate files made by implicit rules whose target patterns match
that file's name; see *Note Interrupts::.
A chain can involve more than two implicit rules. For example, it is
possible to make a file `foo' from `RCS/foo.y,v' by running RCS, Yacc
and `cc'. Then both `foo.y' and `foo.c' are intermediate files that
are deleted at the end.
No single implicit rule can appear more than once in a chain. This
means that `make' will not even consider such a ridiculous thing as
making `foo' from `foo.o.o' by running the linker twice. This
constraint has the added benefit of preventing any infinite loop in the
search for an implicit rule chain.
There are some special implicit rules to optimize certain cases that
would otherwise be handled by rule chains. For example, making `foo'
from `foo.c' could be handled by compiling and linking with separate
chained rules, using `foo.o' as an intermediate file. But what
actually happens is that a special rule for this case does the
compilation and linking with a single `cc' command. The optimized rule
is used in preference to the step-by-step chain because it comes
earlier in the ordering of rules.
Finally, for performance reasons `make' will not consider
non-terminal match-anything rules (i.e., `%:') when searching for a
rule to build a prerequisite of an implicit rule (*note Match-Anything
Rules::).

File: make.info, Node: Pattern Rules, Next: Last Resort, Prev: Chained Rules, Up: Implicit Rules
10.5 Defining and Redefining Pattern Rules
==========================================
You define an implicit rule by writing a "pattern rule". A pattern
rule looks like an ordinary rule, except that its target contains the
character `%' (exactly one of them). The target is considered a
pattern for matching file names; the `%' can match any nonempty
substring, while other characters match only themselves. The
prerequisites likewise use `%' to show how their names relate to the
target name.
Thus, a pattern rule `%.o : %.c' says how to make any file `STEM.o'
from another file `STEM.c'.
Note that expansion using `%' in pattern rules occurs *after* any
variable or function expansions, which take place when the makefile is
read. *Note How to Use Variables: Using Variables, and *Note Functions
for Transforming Text: Functions.
* Menu:
* Pattern Intro:: An introduction to pattern rules.
* Pattern Examples:: Examples of pattern rules.
* Automatic Variables:: How to use automatic variables in the
recipe of implicit rules.
* Pattern Match:: How patterns match.
* Match-Anything Rules:: Precautions you should take prior to
defining rules that can match any
target file whatever.
* Canceling Rules:: How to override or cancel built-in rules.

File: make.info, Node: Pattern Intro, Next: Pattern Examples, Prev: Pattern Rules, Up: Pattern Rules
10.5.1 Introduction to Pattern Rules
------------------------------------
A pattern rule contains the character `%' (exactly one of them) in the
target; otherwise, it looks exactly like an ordinary rule. The target
is a pattern for matching file names; the `%' matches any nonempty
substring, while other characters match only themselves.
For example, `%.c' as a pattern matches any file name that ends in
`.c'. `s.%.c' as a pattern matches any file name that starts with
`s.', ends in `.c' and is at least five characters long. (There must
be at least one character to match the `%'.) The substring that the
`%' matches is called the "stem".
`%' in a prerequisite of a pattern rule stands for the same stem
that was matched by the `%' in the target. In order for the pattern
rule to apply, its target pattern must match the file name under
consideration and all of its prerequisites (after pattern substitution)
must name files that exist or can be made. These files become
prerequisites of the target.
Thus, a rule of the form
%.o : %.c ; RECIPE...
specifies how to make a file `N.o', with another file `N.c' as its
prerequisite, provided that `N.c' exists or can be made.
There may also be prerequisites that do not use `%'; such a
prerequisite attaches to every file made by this pattern rule. These
unvarying prerequisites are useful occasionally.
A pattern rule need not have any prerequisites that contain `%', or
in fact any prerequisites at all. Such a rule is effectively a general
wildcard. It provides a way to make any file that matches the target
pattern. *Note Last Resort::.
More than one pattern rule may match a target. In this case `make'
will choose the "best fit" rule. *Note How Patterns Match: Pattern
Match.
Pattern rules may have more than one target; however, every target
must contain a `%' character. Pattern rules are always treated as
grouped targets (*note Multiple Targets in a Rule: Multiple Targets.)
regardless of whether they use the `:' or `&:' separator.

File: make.info, Node: Pattern Examples, Next: Automatic Variables, Prev: Pattern Intro, Up: Pattern Rules
10.5.2 Pattern Rule Examples
----------------------------
Here are some examples of pattern rules actually predefined in `make'.
First, the rule that compiles `.c' files into `.o' files:
%.o : %.c
$(CC) -c $(CFLAGS) $(CPPFLAGS) $< -o $@
defines a rule that can make any file `X.o' from `X.c'. The recipe
uses the automatic variables `$@' and `$<' to substitute the names of
the target file and the source file in each case where the rule applies
(*note Automatic Variables::).
Here is a second built-in rule:
% :: RCS/%,v
$(CO) $(COFLAGS) $<
defines a rule that can make any file `X' whatsoever from a
corresponding file `X,v' in the sub-directory `RCS'. Since the target
is `%', this rule will apply to any file whatever, provided the
appropriate prerequisite file exists. The double colon makes the rule
"terminal", which means that its prerequisite may not be an intermediate
file (*note Match-Anything Pattern Rules: Match-Anything Rules.).
This pattern rule has two targets:
%.tab.c %.tab.h: %.y
bison -d $<
This tells `make' that the recipe `bison -d X.y' will make both
`X.tab.c' and `X.tab.h'. If the file `foo' depends on the files
`parse.tab.o' and `scan.o' and the file `scan.o' depends on the file
`parse.tab.h', when `parse.y' is changed, the recipe `bison -d parse.y'
will be executed only once, and the prerequisites of both `parse.tab.o'
and `scan.o' will be satisfied. (Presumably the file `parse.tab.o'
will be recompiled from `parse.tab.c' and the file `scan.o' from
`scan.c', while `foo' is linked from `parse.tab.o', `scan.o', and its
other prerequisites, and it will execute happily ever after.)

File: make.info, Node: Automatic Variables, Next: Pattern Match, Prev: Pattern Examples, Up: Pattern Rules
10.5.3 Automatic Variables
--------------------------
Suppose you are writing a pattern rule to compile a `.c' file into a
`.o' file: how do you write the `cc' command so that it operates on the
right source file name? You cannot write the name in the recipe,
because the name is different each time the implicit rule is applied.
What you do is use a special feature of `make', the "automatic
variables". These variables have values computed afresh for each rule
that is executed, based on the target and prerequisites of the rule.
In this example, you would use `$@' for the object file name and `$<'
for the source file name.
It's very important that you recognize the limited scope in which
automatic variable values are available: they only have values within
the recipe. In particular, you cannot use them anywhere within the
target list of a rule; they have no value there and will expand to the
empty string. Also, they cannot be accessed directly within the
prerequisite list of a rule. A common mistake is attempting to use
`$@' within the prerequisites list; this will not work. However, there
is a special feature of GNU `make', secondary expansion (*note
Secondary Expansion::), which will allow automatic variable values to
be used in prerequisite lists.
Here is a table of automatic variables:
`$@'
The file name of the target of the rule. If the target is an
archive member, then `$@' is the name of the archive file. In a
pattern rule that has multiple targets (*note Introduction to
Pattern Rules: Pattern Intro.), `$@' is the name of whichever
target caused the rule's recipe to be run.
`$%'
The target member name, when the target is an archive member.
*Note Archives::. For example, if the target is `foo.a(bar.o)'
then `$%' is `bar.o' and `$@' is `foo.a'. `$%' is empty when the
target is not an archive member.
`$<'
The name of the first prerequisite. If the target got its recipe
from an implicit rule, this will be the first prerequisite added
by the implicit rule (*note Implicit Rules::).
`$?'
The names of all the prerequisites that are newer than the target,
with spaces between them. If the target does not exist, all
prerequisites will be included. For prerequisites which are
archive members, only the named member is used (*note Archives::).
`$^'
The names of all the prerequisites, with spaces between them. For
prerequisites which are archive members, only the named member is
used (*note Archives::). A target has only one prerequisite on
each other file it depends on, no matter how many times each file
is listed as a prerequisite. So if you list a prerequisite more
than once for a target, the value of `$^' contains just one copy
of the name. This list does *not* contain any of the order-only
prerequisites; for those see the `$|' variable, below.
`$+'
This is like `$^', but prerequisites listed more than once are
duplicated in the order they were listed in the makefile. This is
primarily useful for use in linking commands where it is
meaningful to repeat library file names in a particular order.
`$|'
The names of all the order-only prerequisites, with spaces between
them.
`$*'
The stem with which an implicit rule matches (*note How Patterns
Match: Pattern Match.). If the target is `dir/a.foo.b' and the
target pattern is `a.%.b' then the stem is `dir/foo'. The stem is
useful for constructing names of related files.
In a static pattern rule, the stem is part of the file name that
matched the `%' in the target pattern.
In an explicit rule, there is no stem; so `$*' cannot be determined
in that way. Instead, if the target name ends with a recognized
suffix (*note Old-Fashioned Suffix Rules: Suffix Rules.), `$*' is
set to the target name minus the suffix. For example, if the
target name is `foo.c', then `$*' is set to `foo', since `.c' is a
suffix. GNU `make' does this bizarre thing only for compatibility
with other implementations of `make'. You should generally avoid
using `$*' except in implicit rules or static pattern rules.
If the target name in an explicit rule does not end with a
recognized suffix, `$*' is set to the empty string for that rule.
`$?' is useful even in explicit rules when you wish to operate on
only the prerequisites that have changed. For example, suppose that an
archive named `lib' is supposed to contain copies of several object
files. This rule copies just the changed object files into the archive:
lib: foo.o bar.o lose.o win.o
ar r lib $?
Of the variables listed above, four have values that are single file
names, and three have values that are lists of file names. These seven
have variants that get just the file's directory name or just the file
name within the directory. The variant variables' names are formed by
appending `D' or `F', respectively. The functions `dir' and `notdir'
can be used to obtain a similar effect (*note Functions for File Names:
File Name Functions.). Note, however, that the `D' variants all omit
the trailing slash which always appears in the output of the `dir'
function. Here is a table of the variants:
`$(@D)'
The directory part of the file name of the target, with the
trailing slash removed. If the value of `$@' is `dir/foo.o' then
`$(@D)' is `dir'. This value is `.' if `$@' does not contain a
slash.
`$(@F)'
The file-within-directory part of the file name of the target. If
the value of `$@' is `dir/foo.o' then `$(@F)' is `foo.o'. `$(@F)'
is equivalent to `$(notdir $@)'.
`$(*D)'
`$(*F)'
The directory part and the file-within-directory part of the stem;
`dir' and `foo' in this example.
`$(%D)'
`$(%F)'
The directory part and the file-within-directory part of the target
archive member name. This makes sense only for archive member
targets of the form `ARCHIVE(MEMBER)' and is useful only when
MEMBER may contain a directory name. (*Note Archive Members as
Targets: Archive Members.)
`$(<D)'
`$(<F)'
The directory part and the file-within-directory part of the first
prerequisite.
`$(^D)'
`$(^F)'
Lists of the directory parts and the file-within-directory parts
of all prerequisites.
`$(+D)'
`$(+F)'
Lists of the directory parts and the file-within-directory parts
of all prerequisites, including multiple instances of duplicated
prerequisites.
`$(?D)'
`$(?F)'
Lists of the directory parts and the file-within-directory parts of
all prerequisites that are newer than the target.
Note that we use a special stylistic convention when we talk about
these automatic variables; we write "the value of `$<'", rather than
"the variable `<'" as we would write for ordinary variables such as
`objects' and `CFLAGS'. We think this convention looks more natural in
this special case. Please do not assume it has a deep significance;
`$<' refers to the variable named `<' just as `$(CFLAGS)' refers to the
variable named `CFLAGS'. You could just as well use `$(<)' in place of
`$<'.

File: make.info, Node: Pattern Match, Next: Match-Anything Rules, Prev: Automatic Variables, Up: Pattern Rules
10.5.4 How Patterns Match
-------------------------
A target pattern is composed of a `%' between a prefix and a suffix,
either or both of which may be empty. The pattern matches a file name
only if the file name starts with the prefix and ends with the suffix,
without overlap. The text between the prefix and the suffix is called
the "stem". Thus, when the pattern `%.o' matches the file name
`test.o', the stem is `test'. The pattern rule prerequisites are
turned into actual file names by substituting the stem for the character
`%'. Thus, if in the same example one of the prerequisites is written
as `%.c', it expands to `test.c'.
When the target pattern does not contain a slash (and it usually does
not), directory names in the file names are removed from the file name
before it is compared with the target prefix and suffix. After the
comparison of the file name to the target pattern, the directory names,
along with the slash that ends them, are added on to the prerequisite
file names generated from the pattern rule's prerequisite patterns and
the file name. The directories are ignored only for the purpose of
finding an implicit rule to use, not in the application of that rule.
Thus, `e%t' matches the file name `src/eat', with `src/a' as the stem.
When prerequisites are turned into file names, the directories from the
stem are added at the front, while the rest of the stem is substituted
for the `%'. The stem `src/a' with a prerequisite pattern `c%r' gives
the file name `src/car'.
A pattern rule can be used to build a given file only if there is a
target pattern that matches the file name, _and_ all prerequisites in
that rule either exist or can be built. The rules you write take
precedence over those that are built in. Note however, that a rule
whose prerequisites actually exist or are mentioned always takes
priority over a rule with prerequisites that must be made by chaining
other implicit rules.
It is possible that more than one pattern rule will meet these
criteria. In that case, `make' will choose the rule with the shortest
stem (that is, the pattern that matches most specifically). If more
than one pattern rule has the shortest stem, `make' will choose the
first one found in the makefile.
This algorithm results in more specific rules being preferred over
more generic ones; for example:
%.o: %.c
$(CC) -c $(CFLAGS) $(CPPFLAGS) $< -o $@
%.o : %.f
$(COMPILE.F) $(OUTPUT_OPTION) $<
lib/%.o: lib/%.c
$(CC) -fPIC -c $(CFLAGS) $(CPPFLAGS) $< -o $@
Given these rules and asked to build `bar.o' where both `bar.c' and
`bar.f' exist, `make' will choose the first rule and compile `bar.c'
into `bar.o'. In the same situation where `bar.c' does not exist, then
`make' will choose the second rule and compile `bar.f' into `bar.o'.
If `make' is asked to build `lib/bar.o' and both `lib/bar.c' and
`lib/bar.f' exist, then the third rule will be chosen since the stem
for this rule (`bar') is shorter than the stem for the first rule
(`lib/bar'). If `lib/bar.c' does not exist then the third rule is not
eligible and the second rule will be used, even though the stem is
longer.

File: make.info, Node: Match-Anything Rules, Next: Canceling Rules, Prev: Pattern Match, Up: Pattern Rules
10.5.5 Match-Anything Pattern Rules
-----------------------------------
When a pattern rule's target is just `%', it matches any file name
whatever. We call these rules "match-anything" rules. They are very
useful, but it can take a lot of time for `make' to think about them,
because it must consider every such rule for each file name listed
either as a target or as a prerequisite.
Suppose the makefile mentions `foo.c'. For this target, `make'
would have to consider making it by linking an object file `foo.c.o',
or by C compilation-and-linking in one step from `foo.c.c', or by
Pascal compilation-and-linking from `foo.c.p', and many other
possibilities.
We know these possibilities are ridiculous since `foo.c' is a C
source file, not an executable. If `make' did consider these
possibilities, it would ultimately reject them, because files such as
`foo.c.o' and `foo.c.p' would not exist. But these possibilities are so
numerous that `make' would run very slowly if it had to consider them.
To gain speed, we have put various constraints on the way `make'
considers match-anything rules. There are two different constraints
that can be applied, and each time you define a match-anything rule you
must choose one or the other for that rule.
One choice is to mark the match-anything rule as "terminal" by
defining it with a double colon. When a rule is terminal, it does not
apply unless its prerequisites actually exist. Prerequisites that
could be made with other implicit rules are not good enough. In other
words, no further chaining is allowed beyond a terminal rule.
For example, the built-in implicit rules for extracting sources from
RCS and SCCS files are terminal; as a result, if the file `foo.c,v' does
not exist, `make' will not even consider trying to make it as an
intermediate file from `foo.c,v.o' or from `RCS/SCCS/s.foo.c,v'. RCS
and SCCS files are generally ultimate source files, which should not be
remade from any other files; therefore, `make' can save time by not
looking for ways to remake them.
If you do not mark the match-anything rule as terminal, then it is
non-terminal. A non-terminal match-anything rule cannot apply to a
prerequisite of an implicit rule, or to a file name that indicates a
specific type of data. A file name indicates a specific type of data
if some non-match-anything implicit rule target matches it.
For example, the file name `foo.c' matches the target for the pattern
rule `%.c : %.y' (the rule to run Yacc). Regardless of whether this
rule is actually applicable (which happens only if there is a file
`foo.y'), the fact that its target matches is enough to prevent
consideration of any non-terminal match-anything rules for the file
`foo.c'. Thus, `make' will not even consider trying to make `foo.c' as
an executable file from `foo.c.o', `foo.c.c', `foo.c.p', etc.
The motivation for this constraint is that non-terminal
match-anything rules are used for making files containing specific
types of data (such as executable files) and a file name with a
recognized suffix indicates some other specific type of data (such as a
C source file).
Special built-in dummy pattern rules are provided solely to recognize
certain file names so that non-terminal match-anything rules will not be
considered. These dummy rules have no prerequisites and no recipes, and
they are ignored for all other purposes. For example, the built-in
implicit rule
%.p :
exists to make sure that Pascal source files such as `foo.p' match a
specific target pattern and thereby prevent time from being wasted
looking for `foo.p.o' or `foo.p.c'.
Dummy pattern rules such as the one for `%.p' are made for every
suffix listed as valid for use in suffix rules (*note Old-Fashioned
Suffix Rules: Suffix Rules.).

File: make.info, Node: Canceling Rules, Prev: Match-Anything Rules, Up: Pattern Rules
10.5.6 Canceling Implicit Rules
-------------------------------
You can override a built-in implicit rule (or one you have defined
yourself) by defining a new pattern rule with the same target and
prerequisites, but a different recipe. When the new rule is defined,
the built-in one is replaced. The new rule's position in the sequence
of implicit rules is determined by where you write the new rule.
You can cancel a built-in implicit rule by defining a pattern rule
with the same target and prerequisites, but no recipe. For example,
the following would cancel the rule that runs the assembler:
%.o : %.s

File: make.info, Node: Last Resort, Next: Suffix Rules, Prev: Pattern Rules, Up: Implicit Rules
10.6 Defining Last-Resort Default Rules
=======================================
You can define a last-resort implicit rule by writing a terminal
match-anything pattern rule with no prerequisites (*note Match-Anything
Rules::). This is just like any other pattern rule; the only thing
special about it is that it will match any target. So such a rule's
recipe is used for all targets and prerequisites that have no recipe of
their own and for which no other implicit rule applies.
For example, when testing a makefile, you might not care if the
source files contain real data, only that they exist. Then you might
do this:
%::
touch $@
to cause all the source files needed (as prerequisites) to be created
automatically.
You can instead define a recipe to be used for targets for which
there are no rules at all, even ones which don't specify recipes. You
do this by writing a rule for the target `.DEFAULT'. Such a rule's
recipe is used for all prerequisites which do not appear as targets in
any explicit rule, and for which no implicit rule applies. Naturally,
there is no `.DEFAULT' rule unless you write one.
If you use `.DEFAULT' with no recipe or prerequisites:
.DEFAULT:
the recipe previously stored for `.DEFAULT' is cleared. Then `make'
acts as if you had never defined `.DEFAULT' at all.
If you do not want a target to get the recipe from a match-anything
pattern rule or `.DEFAULT', but you also do not want any recipe to be
run for the target, you can give it an empty recipe (*note Defining
Empty Recipes: Empty Recipes.).
You can use a last-resort rule to override part of another makefile.
*Note Overriding Part of Another Makefile: Overriding Makefiles.

File: make.info, Node: Suffix Rules, Next: Implicit Rule Search, Prev: Last Resort, Up: Implicit Rules
10.7 Old-Fashioned Suffix Rules
===============================
"Suffix rules" are the old-fashioned way of defining implicit rules for
`make'. Suffix rules are obsolete because pattern rules are more
general and clearer. They are supported in GNU `make' for
compatibility with old makefiles. They come in two kinds:
"double-suffix" and "single-suffix".
A double-suffix rule is defined by a pair of suffixes: the target
suffix and the source suffix. It matches any file whose name ends with
the target suffix. The corresponding implicit prerequisite is made by
replacing the target suffix with the source suffix in the file name. A
two-suffix rule `.c.o' (whose target and source suffixes are `.o' and
`.c') is equivalent to the pattern rule `%.o : %.c'.
A single-suffix rule is defined by a single suffix, which is the
source suffix. It matches any file name, and the corresponding implicit
prerequisite name is made by appending the source suffix. A
single-suffix rule whose source suffix is `.c' is equivalent to the
pattern rule `% : %.c'.
Suffix rule definitions are recognized by comparing each rule's
target against a defined list of known suffixes. When `make' sees a
rule whose target is a known suffix, this rule is considered a
single-suffix rule. When `make' sees a rule whose target is two known
suffixes concatenated, this rule is taken as a double-suffix rule.
For example, `.c' and `.o' are both on the default list of known
suffixes. Therefore, if you define a rule whose target is `.c.o',
`make' takes it to be a double-suffix rule with source suffix `.c' and
target suffix `.o'. Here is the old-fashioned way to define the rule
for compiling a C source file:
.c.o:
$(CC) -c $(CFLAGS) $(CPPFLAGS) -o $@ $<
Suffix rules cannot have any prerequisites of their own. If they
have any, they are treated as normal files with funny names, not as
suffix rules. Thus, the rule:
.c.o: foo.h
$(CC) -c $(CFLAGS) $(CPPFLAGS) -o $@ $<
tells how to make the file `.c.o' from the prerequisite file `foo.h',
and is not at all like the pattern rule:
%.o: %.c foo.h
$(CC) -c $(CFLAGS) $(CPPFLAGS) -o $@ $<
which tells how to make `.o' files from `.c' files, and makes all `.o'
files using this pattern rule also depend on `foo.h'.
Suffix rules with no recipe are also meaningless. They do not remove
previous rules as do pattern rules with no recipe (*note Canceling
Implicit Rules: Canceling Rules.). They simply enter the suffix or
pair of suffixes concatenated as a target in the data base.
The known suffixes are simply the names of the prerequisites of the
special target `.SUFFIXES'. You can add your own suffixes by writing a
rule for `.SUFFIXES' that adds more prerequisites, as in:
.SUFFIXES: .hack .win
which adds `.hack' and `.win' to the end of the list of suffixes.
If you wish to eliminate the default known suffixes instead of just
adding to them, write a rule for `.SUFFIXES' with no prerequisites. By
special dispensation, this eliminates all existing prerequisites of
`.SUFFIXES'. You can then write another rule to add the suffixes you
want. For example,
.SUFFIXES: # Delete the default suffixes
.SUFFIXES: .c .o .h # Define our suffix list
The `-r' or `--no-builtin-rules' flag causes the default list of
suffixes to be empty.
The variable `SUFFIXES' is defined to the default list of suffixes
before `make' reads any makefiles. You can change the list of suffixes
with a rule for the special target `.SUFFIXES', but that does not alter
this variable.

File: make.info, Node: Implicit Rule Search, Prev: Suffix Rules, Up: Implicit Rules
10.8 Implicit Rule Search Algorithm
===================================
Here is the procedure `make' uses for searching for an implicit rule
for a target T. This procedure is followed for each double-colon rule
with no recipe, for each target of ordinary rules none of which have a
recipe, and for each prerequisite that is not the target of any rule.
It is also followed recursively for prerequisites that come from
implicit rules, in the search for a chain of rules.
Suffix rules are not mentioned in this algorithm because suffix
rules are converted to equivalent pattern rules once the makefiles have
been read in.
For an archive member target of the form `ARCHIVE(MEMBER)', the
following algorithm is run twice, first using the entire target name T,
and second using `(MEMBER)' as the target T if the first run found no
rule.
1. Split T into a directory part, called D, and the rest, called N.
For example, if T is `src/foo.o', then D is `src/' and N is
`foo.o'.
2. Make a list of all the pattern rules one of whose targets matches
T or N. If the target pattern contains a slash, it is matched
against T; otherwise, against N.
3. If any rule in that list is _not_ a match-anything rule, or if T
is a prerequisite of an implicit rule, then remove all
non-terminal match-anything rules from the list.
4. Remove from the list all rules with no recipe.
5. For each pattern rule in the list:
a. Find the stem S, which is the nonempty part of T or N matched
by the `%' in the target pattern.
b. Compute the prerequisite names by substituting S for `%'; if
the target pattern does not contain a slash, append D to the
front of each prerequisite name.
c. Test whether all the prerequisites exist or ought to exist.
(If a file name is mentioned in the makefile as a target or
as an explicit prerequisite, then we say it ought to exist.)
If all prerequisites exist or ought to exist, or there are no
prerequisites, then this rule applies.
6. If no pattern rule has been found so far, try harder. For each
pattern rule in the list:
a. If the rule is terminal, ignore it and go on to the next rule.
b. Compute the prerequisite names as before.
c. Test whether all the prerequisites exist or ought to exist.
d. For each prerequisite that does not exist, follow this
algorithm recursively to see if the prerequisite can be made
by an implicit rule.
e. If all prerequisites exist, ought to exist, or can be made by
implicit rules, then this rule applies.
7. If no implicit rule applies, the rule for `.DEFAULT', if any,
applies. In that case, give T the same recipe that `.DEFAULT'
has. Otherwise, there is no recipe for T.
Once a rule that applies has been found, for each target pattern of
the rule other than the one that matched T or N, the `%' in the pattern
is replaced with S and the resultant file name is stored until the
recipe to remake the target file T is executed. After the recipe is
executed, each of these stored file names are entered into the data
base and marked as having been updated and having the same update
status as the file T.
When the recipe of a pattern rule is executed for T, the automatic
variables are set corresponding to the target and prerequisites. *Note
Automatic Variables::.

File: make.info, Node: Archives, Next: Extending make, Prev: Implicit Rules, Up: Top
11 Using `make' to Update Archive Files
***************************************
"Archive files" are files containing named sub-files called "members";
they are maintained with the program `ar' and their main use is as
subroutine libraries for linking.
* Menu:
* Archive Members:: Archive members as targets.
* Archive Update:: The implicit rule for archive member targets.
* Archive Pitfalls:: Dangers to watch out for when using archives.
* Archive Suffix Rules:: You can write a special kind of suffix rule
for updating archives.

File: make.info, Node: Archive Members, Next: Archive Update, Prev: Archives, Up: Archives
11.1 Archive Members as Targets
===============================
An individual member of an archive file can be used as a target or
prerequisite in `make'. You specify the member named MEMBER in archive
file ARCHIVE as follows:
ARCHIVE(MEMBER)
This construct is available only in targets and prerequisites, not in
recipes! Most programs that you might use in recipes do not support
this syntax and cannot act directly on archive members. Only `ar' and
other programs specifically designed to operate on archives can do so.
Therefore, valid recipes to update an archive member target probably
must use `ar'. For example, this rule says to create a member `hack.o'
in archive `foolib' by copying the file `hack.o':
foolib(hack.o) : hack.o
ar cr foolib hack.o
In fact, nearly all archive member targets are updated in just this
way and there is an implicit rule to do it for you. *Please note:* The
`c' flag to `ar' is required if the archive file does not already exist.
To specify several members in the same archive, you can write all the
member names together between the parentheses. For example:
foolib(hack.o kludge.o)
is equivalent to:
foolib(hack.o) foolib(kludge.o)
You can also use shell-style wildcards in an archive member
reference. *Note Using Wildcard Characters in File Names: Wildcards.
For example, `foolib(*.o)' expands to all existing members of the
`foolib' archive whose names end in `.o'; perhaps `foolib(hack.o)
foolib(kludge.o)'.

File: make.info, Node: Archive Update, Next: Archive Pitfalls, Prev: Archive Members, Up: Archives
11.2 Implicit Rule for Archive Member Targets
=============================================
Recall that a target that looks like `A(M)' stands for the member named
M in the archive file A.
When `make' looks for an implicit rule for such a target, as a
special feature it considers implicit rules that match `(M)', as well as
those that match the actual target `A(M)'.
This causes one special rule whose target is `(%)' to match. This
rule updates the target `A(M)' by copying the file M into the archive.
For example, it will update the archive member target `foo.a(bar.o)' by
copying the _file_ `bar.o' into the archive `foo.a' as a _member_ named
`bar.o'.
When this rule is chained with others, the result is very powerful.
Thus, `make "foo.a(bar.o)"' (the quotes are needed to protect the `('
and `)' from being interpreted specially by the shell) in the presence
of a file `bar.c' is enough to cause the following recipe to be run,
even without a makefile:
cc -c bar.c -o bar.o
ar r foo.a bar.o
rm -f bar.o
Here `make' has envisioned the file `bar.o' as an intermediate file.
*Note Chains of Implicit Rules: Chained Rules.
Implicit rules such as this one are written using the automatic
variable `$%'. *Note Automatic Variables::.
An archive member name in an archive cannot contain a directory
name, but it may be useful in a makefile to pretend that it does. If
you write an archive member target `foo.a(dir/file.o)', `make' will
perform automatic updating with this recipe:
ar r foo.a dir/file.o
which has the effect of copying the file `dir/file.o' into a member
named `file.o'. In connection with such usage, the automatic variables
`%D' and `%F' may be useful.
* Menu:
* Archive Symbols:: How to update archive symbol directories.

File: make.info, Node: Archive Symbols, Prev: Archive Update, Up: Archive Update
11.2.1 Updating Archive Symbol Directories
------------------------------------------
An archive file that is used as a library usually contains a special
member named `__.SYMDEF' that contains a directory of the external
symbol names defined by all the other members. After you update any
other members, you need to update `__.SYMDEF' so that it will summarize
the other members properly. This is done by running the `ranlib'
program:
ranlib ARCHIVEFILE
Normally you would put this command in the rule for the archive file,
and make all the members of the archive file prerequisites of that rule.
For example,
libfoo.a: libfoo.a(x.o) libfoo.a(y.o) ...
ranlib libfoo.a
The effect of this is to update archive members `x.o', `y.o', etc., and
then update the symbol directory member `__.SYMDEF' by running
`ranlib'. The rules for updating the members are not shown here; most
likely you can omit them and use the implicit rule which copies files
into the archive, as described in the preceding section.
This is not necessary when using the GNU `ar' program, which updates
the `__.SYMDEF' member automatically.

File: make.info, Node: Archive Pitfalls, Next: Archive Suffix Rules, Prev: Archive Update, Up: Archives
11.3 Dangers When Using Archives
================================
It is important to be careful when using parallel execution (the `-j'
switch; *note Parallel Execution: Parallel.) and archives. If multiple
`ar' commands run at the same time on the same archive file, they will
not know about each other and can corrupt the file.
Possibly a future version of `make' will provide a mechanism to
circumvent this problem by serializing all recipes that operate on the
same archive file. But for the time being, you must either write your
makefiles to avoid this problem in some other way, or not use `-j'.

File: make.info, Node: Archive Suffix Rules, Prev: Archive Pitfalls, Up: Archives
11.4 Suffix Rules for Archive Files
===================================
You can write a special kind of suffix rule for dealing with archive
files. *Note Suffix Rules::, for a full explanation of suffix rules.
Archive suffix rules are obsolete in GNU `make', because pattern rules
for archives are a more general mechanism (*note Archive Update::).
But they are retained for compatibility with other `make's.
To write a suffix rule for archives, you simply write a suffix rule
using the target suffix `.a' (the usual suffix for archive files). For
example, here is the old-fashioned suffix rule to update a library
archive from C source files:
.c.a:
$(CC) $(CFLAGS) $(CPPFLAGS) -c $< -o $*.o
$(AR) r $@ $*.o
$(RM) $*.o
This works just as if you had written the pattern rule:
(%.o): %.c
$(CC) $(CFLAGS) $(CPPFLAGS) -c $< -o $*.o
$(AR) r $@ $*.o
$(RM) $*.o
In fact, this is just what `make' does when it sees a suffix rule
with `.a' as the target suffix. Any double-suffix rule `.X.a' is
converted to a pattern rule with the target pattern `(%.o)' and a
prerequisite pattern of `%.X'.
Since you might want to use `.a' as the suffix for some other kind
of file, `make' also converts archive suffix rules to pattern rules in
the normal way (*note Suffix Rules::). Thus a double-suffix rule
`.X.a' produces two pattern rules: `(%.o): %.X' and `%.a: %.X'.

File: make.info, Node: Extending make, Next: Integrating make, Prev: Archives, Up: Top
12 Extending GNU `make'
***********************
GNU `make' provides many advanced capabilities, including many useful
functions. However, it does not contain a complete programming
language and so it has limitations. Sometimes these limitations can be
overcome through use of the `shell' function to invoke a separate
program, although this can be inefficient.
In cases where the built-in capabilities of GNU `make' are
insufficient to your requirements there are two options for extending
`make'. On systems where it's provided, you can utilize GNU Guile as
an embedded scripting language (*note GNU Guile Integration: Guile
Integration.). On systems which support dynamically loadable objects,
you can write your own extension in any language (which can be compiled
into such an object) and load it to provide extended capabilities
(*note The `load' Directive: load Directive.).
* Menu:
* Guile Integration:: Using Guile as an embedded scripting language.
* Loading Objects:: Loading dynamic objects as extensions.

File: make.info, Node: Guile Integration, Next: Loading Objects, Prev: Extending make, Up: Extending make
12.1 GNU Guile Integration
==========================
GNU `make' may be built with support for GNU Guile as an embedded
extension language. Guile implements the Scheme language. A review of
GNU Guile and the Scheme language and its features is beyond the scope
of this manual: see the documentation for GNU Guile and Scheme.
You can determine if `make' contains support for Guile by examining
the `.FEATURES' variable; it will contain the word GUILE if Guile
support is available.
The Guile integration provides one new `make' function: `guile'.
The `guile' function takes one argument which is first expanded by
`make' in the normal fashion, then passed to the GNU Guile evaluator.
The result of the evaluator is converted into a string and used as the
expansion of the `guile' function in the makefile.
In addition, GNU `make' exposes Guile procedures for use in Guile
scripts.
* Menu:
* Guile Types:: Converting Guile types to `make' strings.
* Guile Interface:: Invoking `make' functions from Guile.
* Guile Example:: Example using Guile in `make'.

File: make.info, Node: Guile Types, Next: Guile Interface, Prev: Guile Integration, Up: Guile Integration
12.1.1 Conversion of Guile Types
--------------------------------
There is only one "data type" in `make': a string. GNU Guile, on the
other hand, provides a rich variety of different data types. An
important aspect of the interface between `make' and GNU Guile is the
conversion of Guile data types into `make' strings.
This conversion is relevant in two places: when a makefile invokes
the `guile' function to evaluate a Guile expression, the result of that
evaluation must be converted into a make string so it can be further
evaluated by `make'. And secondly, when a Guile script invokes one of
the procedures exported by `make' the argument provided to the
procedure must be converted into a string.
The conversion of Guile types into `make' strings is as below:
`#f'
False is converted into the empty string: in `make' conditionals
the empty string is considered false.
`#t'
True is converted to the string `#t': in `make' conditionals any
non-empty string is considered true.
`symbol'
`number'
A symbol or number is converted into the string representation of
that symbol or number.
`character'
A printable character is converted to the same character.
`string'
A string containing only printable characters is converted to the
same string.
`list'
A list is converted recursively according to the above rules. This
implies that any structured list will be flattened (that is, a
result of `'(a b (c d) e)' will be converted to the `make' string
`a b c d e').
`other'
Any other Guile type results in an error. In future versions of
`make', other Guile types may be converted.
The translation of `#f' (to the empty string) and `#t' (to the
non-empty string `#t') is designed to allow you to use Guile boolean
results directly as `make' boolean conditions. For example:
$(if $(guile (access? "myfile" R_OK)),$(info myfile exists))
As a consequence of these conversion rules you must consider the
result of your Guile script, as that result will be converted into a
string and parsed by `make'. If there is no natural result for the
script (that is, the script exists solely for its side-effects), you
should add `#f' as the final expression in order to avoid syntax errors
in your makefile.

File: make.info, Node: Guile Interface, Next: Guile Example, Prev: Guile Types, Up: Guile Integration
12.1.2 Interfaces from Guile to `make'
--------------------------------------
In addition to the `guile' function available in makefiles, `make'
exposes some procedures for use in your Guile scripts. At startup
`make' creates a new Guile module, `gnu make', and exports these
procedures as public interfaces from that module:
`gmk-expand'
This procedure takes a single argument which is converted into a
string. The string is expanded by `make' using normal `make'
expansion rules. The result of the expansion is converted into a
Guile string and provided as the result of the procedure.
`gmk-eval'
This procedure takes a single argument which is converted into a
string. The string is evaluated by `make' as if it were a
makefile. This is the same capability available via the `eval'
function (*note Eval Function::). The result of the `gmk-eval'
procedure is always the empty string.
Note that `gmk-eval' is not quite the same as using `gmk-expand'
with the `eval' function: in the latter case the evaluated string
will be expanded _twice_; first by `gmk-expand', then again by the
`eval' function.

File: make.info, Node: Guile Example, Prev: Guile Interface, Up: Guile Integration
12.1.3 Example Using Guile in `make'
------------------------------------
Here is a very simple example using GNU Guile to manage writing to a
file. These Guile procedures simply open a file, allow writing to the
file (one string per line), and close the file. Note that because we
cannot store complex values such as Guile ports in `make' variables,
we'll keep the port as a global variable in the Guile interpreter.
You can create Guile functions easily using `define'/`endef' to
create a Guile script, then use the `guile' function to internalize it:
define GUILEIO
;; A simple Guile IO library for GNU make
(define MKPORT #f)
(define (mkopen name mode)
(set! MKPORT (open-file name mode))
#f)
(define (mkwrite s)
(display s MKPORT)
(newline MKPORT)
#f)
(define (mkclose)
(close-port MKPORT)
#f)
#f
endef
# Internalize the Guile IO functions
$(guile $(GUILEIO))
If you have a significant amount of Guile support code, you might
consider keeping it in a different file (e.g., `guileio.scm') and then
loading it in your makefile using the `guile' function:
$(guile (load "guileio.scm"))
An advantage to this method is that when editing `guileio.scm', your
editor will understand that this file contains Scheme syntax rather
than makefile syntax.
Now you can use these Guile functions to create files. Suppose you
need to operate on a very large list, which cannot fit on the command
line, but the utility you're using accepts the list as input as well:
prog: $(PREREQS)
@$(guile (mkopen "tmp.out" "w")) \
$(foreach X,$^,$(guile (mkwrite "$(X)"))) \
$(guile (mkclose))
$(LINK) < tmp.out
A more comprehensive suite of file manipulation procedures is
possible of course. You could, for example, maintain multiple output
files at the same time by choosing a symbol for each one and using it
as the key to a hash table, where the value is a port, then returning
the symbol to be stored in a `make' variable.

File: make.info, Node: Loading Objects, Prev: Guile Integration, Up: Extending make
12.2 Loading Dynamic Objects
============================
Warning: The `load' directive and extension capability is
considered a "technology preview" in this release of GNU make. We
encourage you to experiment with this feature and we appreciate
any feedback on it. However we cannot guarantee to maintain
backward-compatibility in the next release. Consider using GNU
Guile instead for extending GNU make (*note The `guile' Function:
Guile Function.).
Many operating systems provide a facility for dynamically loading
compiled objects. If your system provides this facility, GNU `make'
can make use of it to load dynamic objects at runtime, providing new
capabilities which may then be invoked by your makefile.
The `load' directive is used to load a dynamic object. Once the
object is loaded, a "setup" function will be invoked to allow the
object to initialize itself and register new facilities with GNU
`make'. A dynamic object might include new `make' functions, for
example, and the "setup" function would register them with GNU `make''s
function handling system.
* Menu:
* load Directive:: Loading dynamic objects as extensions.
* Remaking Loaded Objects:: How loaded objects get remade.
* Loaded Object API:: Programmatic interface for loaded objects.
* Loaded Object Example:: Example of a loaded object

File: make.info, Node: load Directive, Next: Remaking Loaded Objects, Prev: Loading Objects, Up: Loading Objects
12.2.1 The `load' Directive
---------------------------
Objects are loaded into GNU `make' by placing the `load' directive into
your makefile. The syntax of the `load' directive is as follows:
load OBJECT-FILE ...
or:
load OBJECT-FILE(SYMBOL-NAME) ...
The file OBJECT-FILE is dynamically loaded by GNU `make'. If
OBJECT-FILE does not include a directory path then it is first looked
for in the current directory. If it is not found there, or a directory
path is included, then system-specific paths will be searched. If the
load fails for any reason, `make' will print a message and exit.
If the load succeeds `make' will invoke an initializing function.
If SYMBOL-NAME is provided, it will be used as the name of the
initializing function.
If no SYMBOL-NAME is provided, the initializing function name is
created by taking the base file name of OBJECT-FILE, up to the first
character which is not a valid symbol name character (alphanumerics and
underscores are valid symbol name characters). To this prefix will be
appended the suffix `_gmk_setup'.
More than one object file may be loaded with a single `load'
directive, and both forms of `load' arguments may be used in the same
directive.
The initializing function will be provided the file name and line
number of the invocation of the `load' operation. It should return a
value of type `int', which must be `0' on failure and non-`0' on
success. If the return value is `-1', then GNU make will _not_ attempt
to rebuild the object file (*note How Loaded Objects Are Remade:
Remaking Loaded Objects.).
For example:
load ../mk_funcs.so
will load the dynamic object `../mk_funcs.so'. After the object is
loaded, `make' will invoke the function (assumed to be defined by the
shared object) `mk_funcs_gmk_setup'.
On the other hand:
load ../mk_funcs.so(init_mk_func)
will load the dynamic object `../mk_funcs.so'. After the object is
loaded, `make' will invoke the function `init_mk_func'.
Regardless of how many times an object file appears in a `load'
directive, it will only be loaded (and its setup function will only be
invoked) once.
After an object has been successfully loaded, its file name is
appended to the `.LOADED' variable.
If you would prefer that failure to load a dynamic object not be
reported as an error, you can use the `-load' directive instead of
`load'. GNU `make' will not fail and no message will be generated if
an object fails to load. The failed object is not added to the
`.LOADED' variable, which can then be consulted to determine if the
load was successful.

File: make.info, Node: Remaking Loaded Objects, Next: Loaded Object API, Prev: load Directive, Up: Loading Objects
12.2.2 How Loaded Objects Are Remade
------------------------------------
Loaded objects undergo the same re-make procedure as makefiles (*note
How Makefiles Are Remade: Remaking Makefiles.). If any loaded object
is recreated, then `make' will start from scratch and re-read all the
makefiles, and reload the object files again. It is not necessary for
the loaded object to do anything special to support this.
It's up to the makefile author to provide the rules needed for
rebuilding the loaded object.

File: make.info, Node: Loaded Object API, Next: Loaded Object Example, Prev: Remaking Loaded Objects, Up: Loading Objects
12.2.3 Loaded Object Interface
------------------------------
Warning: For this feature to be useful your extensions will need
to invoke various functions internal to GNU `make'. The
programming interfaces provided in this release should not be
considered stable: functions may be added, removed, or change
calling signatures or implementations in future versions of GNU
`make'.
To be useful, loaded objects must be able to interact with GNU `make'.
This interaction includes both interfaces the loaded object provides to
makefiles and also interfaces `make' provides to the loaded object to
manipulate `make''s operation.
The interface between loaded objects and `make' is defined by the
`gnumake.h' C header file. All loaded objects written in C should
include this header file. Any loaded object not written in C will need
to implement the interface defined in this header file.
Typically, a loaded object will register one or more new GNU `make'
functions using the `gmk_add_function' routine from within its setup
function. The implementations of these `make' functions may make use
of the `gmk_expand' and `gmk_eval' routines to perform their tasks,
then optionally return a string as the result of the function expansion.
Loaded Object Licensing
.......................
Every dynamic extension should define the global symbol
`plugin_is_GPL_compatible' to assert that it has been licensed under a
GPL-compatible license. If this symbol does not exist, `make' emits a
fatal error and exits when it tries to load your extension.
The declared type of the symbol should be `int'. It does not need to
be in any allocated section, though. The code merely asserts that the
symbol exists in the global scope. Something like this is enough:
int plugin_is_GPL_compatible;
Data Structures
...............
`gmk_floc'
This structure represents a filename/location pair. It is provided
when defining items, so GNU `make' can inform the user later where
the definition occurred if necessary.
Registering Functions
.....................
There is currently one way for makefiles to invoke operations provided
by the loaded object: through the `make' function call interface. A
loaded object can register one or more new functions which may then be
invoked from within the makefile in the same way as any other function.
Use `gmk_add_function' to create a new `make' function. Its
arguments are as follows:
`name'
The function name. This is what the makefile should use to invoke
the function. The name must be between 1 and 255 characters long
and it may only contain alphanumeric, period (`.'), dash (`-'), and
underscore (`_') characters. It may not begin with a period.
`func_ptr'
A pointer to a function that `make' will invoke when it expands
the function in a makefile. This function must be defined by the
loaded object.
`min_args'
The minimum number of arguments the function will accept. Must be
between 0 and 255. GNU `make' will check this and fail before
invoking `func_ptr' if the function was invoked with too few
arguments.
`max_args'
The maximum number of arguments the function will accept. Must be
between 0 and 255. GNU `make' will check this and fail before
invoking `func_ptr' if the function was invoked with too few
arguments. If the value is 0, then any number of arguments is
accepted. If the value is greater than 0, then it must be greater
than or equal to `min_args'.
`flags'
Flags that specify how this function will operate; the desired
flags should be OR'd together. If the `GMK_FUNC_NOEXPAND' flag is
given then the function arguments will not be expanded before the
function is called; otherwise they will be expanded first.
Registered Function Interface
.............................
A function registered with `make' must match the `gmk_func_ptr' type.
It will be invoked with three parameters: `name' (the name of the
function), `argc' (the number of arguments to the function), and `argv'
(an array of pointers to arguments to the function). The last pointer
(that is, `argv[argc]') will be null (`0').
The return value of the function is the result of expanding the
function. If the function expands to nothing the return value may be
null. Otherwise, it must be a pointer to a string created with
`gmk_alloc'. Once the function returns, `make' owns this string and
will free it when appropriate; it cannot be accessed by the loaded
object.
GNU `make' Facilities
.....................
There are some facilities exported by GNU `make' for use by loaded
objects. Typically these would be run from within the setup function
and/or the functions registered via `gmk_add_function', to retrieve or
modify the data `make' works with.
`gmk_expand'
This function takes a string and expands it using `make' expansion
rules. The result of the expansion is returned in a
nil-terminated string buffer. The caller is responsible for
calling `gmk_free' with a pointer to the returned buffer when done.
`gmk_eval'
This function takes a buffer and evaluates it as a segment of
makefile syntax. This function can be used to define new
variables, new rules, etc. It is equivalent to using the `eval'
`make' function.
Note that there is a difference between `gmk_eval' and calling
`gmk_expand' with a string using the `eval' function: in the latter
case the string will be expanded _twice_; once by `gmk_expand' and then
again by the `eval' function. Using `gmk_eval' the buffer is only
expanded once, at most (as it's read by the `make' parser).
Memory Management
.................
Some systems allow for different memory management schemes. Thus you
should never pass memory that you've allocated directly to any `make'
function, nor should you attempt to directly free any memory returned
to you by any `make' function. Instead, use the `gmk_alloc' and
`gmk_free' functions.
In particular, the string returned to `make' by a function
registered using `gmk_add_function' _must_ be allocated using
`gmk_alloc', and the string returned from the `make' `gmk_expand'
function _must_ be freed (when no longer needed) using `gmk_free'.
`gmk_alloc'
Return a pointer to a newly-allocated buffer. This function will
always return a valid pointer; if not enough memory is available
`make' will exit.
`gmk_free'
Free a buffer returned to you by `make'. Once the `gmk_free'
function returns the string will no longer be valid.

File: make.info, Node: Loaded Object Example, Prev: Loaded Object API, Up: Loading Objects
12.2.4 Example Loaded Object
----------------------------
Let's suppose we wanted to write a new GNU `make' function that would
create a temporary file and return its name. We would like our
function to take a prefix as an argument. First we can write the
function in a file `mk_temp.c':
#include <stdlib.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <gnumake.h>
int plugin_is_GPL_compatible;
char *
gen_tmpfile(const char *nm, int argc, char **argv)
{
int fd;
/* Compute the size of the filename and allocate space for it. */
int len = strlen (argv[0]) + 6 + 1;
char *buf = gmk_alloc (len);
strcpy (buf, argv[0]);
strcat (buf, "XXXXXX");
fd = mkstemp(buf);
if (fd >= 0)
{
/* Don't leak the file descriptor. */
close (fd);
return buf;
}
/* Failure. */
fprintf (stderr, "mkstemp(%s) failed: %s\n", buf, strerror (errno));
gmk_free (buf);
return NULL;
}
int
mk_temp_gmk_setup ()
{
/* Register the function with make name "mk-temp". */
gmk_add_function ("mk-temp", gen_tmpfile, 1, 1, 1);
return 1;
}
Next, we will write a makefile that can build this shared object,
load it, and use it:
all:
@echo Temporary file: $(mk-temp tmpfile.)
load mk_temp.so
mk_temp.so: mk_temp.c
$(CC) -shared -fPIC -o $ $<
On MS-Windows, due to peculiarities of how shared objects are
produced, the compiler needs to scan the "import library" produced when
building `make', typically called `libgnumake-VERSION.dll.a', where
VERSION is the version of the load object API. So the recipe to
produce a shared object will look on Windows like this (assuming the
API version is 1):
mk_temp.dll: mk_temp.c
$(CC) -shared -o $ $< -lgnumake-1
Now when you run `make' you'll see something like:
$ make
cc -shared -fPIC -o mk_temp.so mk_temp.c
Temporary filename: tmpfile.A7JEwd

File: make.info, Node: Integrating make, Next: Features, Prev: Extending make, Up: Top
13 Integrating GNU `make'
*************************
GNU `make' is often one component in a larger system of tools,
including integrated development environments, compiler toolchains, and
others. The role of `make' is to start commands and determine whether
they succeeded or not: no special integration is needed to accomplish
that. However, sometimes it is convenient to bind `make' more tightly
with other parts of the system, both higher-level (tools that invoke
`make') and lower-level (tools that `make' invokes).
* Menu:
* Job Slots:: Share job slots with GNU `make'.
* Terminal Output:: Control output to terminals.

File: make.info, Node: Job Slots, Next: Terminal Output, Prev: Integrating make, Up: Integrating make
13.1 Sharing Job Slots with GNU `make'
======================================
GNU `make' has the ability to run multiple recipes in parallel (*note
Parallel Execution: Parallel.) and to cap the total number of parallel
jobs even across recursive invocations of `make' (*note Communicating
Options to a Sub-`make': Options/Recursion.). Tools that `make'
invokes which are also able to run multiple operations in parallel,
either using multiple threads or multiple processes, can be enhanced to
participate in GNU `make''s job management facility to ensure that the
total number of active threads/processes running on the system does not
exceed the maximum number of slots provided to GNU `make'.
GNU `make' uses a method called the "jobserver" to control the
number of active jobs across recursive invocations. The actual
implementation of the jobserver varies across different operating
systems, but some fundamental aspects are always true.
First, only command lines that `make' understands to be recursive
invocations of `make' (*note How the `MAKE' Variable Works: MAKE
Variable.) will have access to the jobserver. When writing makefiles
you must be sure to mark the command as recursive (most commonly by
prefixing the command line with the `+' indicator (*note Recursive Use
of `make': Recursion.).
Second, `make' will provide information necessary for accessing the
jobserver through the environment to its children, in the `MAKEFLAGS'
environment variable. Tools which want to participate in the jobserver
protocol will need to parse this environment variable, as described in
subsequent sections.
Third, every command `make' starts has one implicit job slot
reserved for it before it starts. Any tool which wants to participate
in the jobserver protocol should assume it can always run one job
without having to contact the jobserver at all.
Finally, it's critical that tools that participate in the jobserver
protocol return the exact number of slots they obtained from the
jobserver back to the jobserver before they exit, even under error
conditions. Remember that the implicit job slot should *not* be
returned to the jobserver! Returning too few slots means that those
slots will be lost for the rest of the build process; returning too
many slots means that extra slots will be available. The top-level
`make' command will print an error message at the end of the build if
it detects an incorrect number of slots available in the jobserver.
As an example, suppose you are implementing a linker which provides
for multithreaded operation. You would like to enhance the linker so
that if it is invoked by GNU `make' it can participate in the jobserver
protocol to control how many threads are used during link. First you
will need to modify the linker to determine if the `MAKEFLAGS'
environment variable is set. Next you will need to parse the value of
that variable to determine if the jobserver is available, and how to
access it. If it is available then you can access it to obtain job
slots controlling how much parallelism your tool can use. Once done
your tool must return those job slots back to the jobserver.
* Menu:
* POSIX Jobserver:: Using the jobserver on POSIX systems.
* Windows Jobserver:: Using the jobserver on Windows systems.

File: make.info, Node: POSIX Jobserver, Next: Windows Jobserver, Prev: Job Slots, Up: Job Slots
13.1.1 POSIX Jobserver Interaction
----------------------------------
On POSIX systems the jobserver is implemented as a simple UNIX pipe.
The pipe will be pre-loaded with one single-character token for each
available job. To obtain an extra slot you must read a single
character from the jobserver pipe; to release a slot you must write a
single character back into the jobserver pipe. Note that the read side
of the jobserver pipe is set to "blocking" mode.
To access the pipe you must parse the `MAKEFLAGS' variable and look
for the argument string `--jobserver-auth=R,W' where `R' and `W' are
non-negative integers representing file descriptors: `R' is the read
file descriptor and `W' is the write file descriptor.
It's important that when you release the job slot, you write back the
same character you read from the pipe for that slot. Don't assume that
all tokens are the same character; different characters may have
different meanings to GNU `make'. The order is not important, since
`make' has no idea in what order jobs will complete anyway.
There are various error conditions you must consider to ensure your
implementation is robust:
* Usually you will have a command-line argument controlling the
parallel operation of your tool. Consider whether your tool
should detect situations where both the jobserver and the
command-line argument are specified, and how it should react.
* If your tool determines that the `--jobserver-auth' option is
available in `MAKEFLAGS' but that the file descriptors specified
are closed, this means that the calling `make' process did not
think that your tool was a recursive `make' invocation (e.g., the
command line was not prefixed with a `+' character). You should
notify your users of this situation.
* Your tool should also examine the first word of the `MAKEFLAGS'
variable and look for the character `n'. If this character is
present then `make' was invoked with the `-n' option and your tool
should stop without performing any operations.
* Your tool should be sure to write back the tokens it read, even
under error conditions. This includes not only errors in your
tool but also outside influences such as interrupts (`SIGINT'),
etc. You may want to install signal handlers to manage this
write-back.

File: make.info, Node: Windows Jobserver, Prev: POSIX Jobserver, Up: Job Slots
13.1.2 Windows Jobserver Interaction
------------------------------------
On Windows systems the jobserver is implemented as a named semaphore.
The semaphore will be set with an initial count equal to the number of
available slots; to obtain a slot you must wait on the semaphore (with
or without a timeout). To release a slot, release the semaphore.
To access the semaphore you must parse the `MAKEFLAGS' variable and
look for the argument string `--jobserver-auth=NAME' where `NAME' is
the name of the named semaphore. Use this name with `OpenSemaphore' to
create a handle to the semaphore.
There are various error conditions you must consider to ensure your
implementation is robust:
* Usually you will have a command-line argument controlling the
parallel operation of your tool. Consider whether your tool
should detect situations where both the jobserver and the
command-line argument are specified, and how it should react.
* Your tool should be sure to release the semaphore for the tokens it
read, even under error conditions. This includes not only errors
in your tool but also outside influences such as interrupts
(`SIGINT'), etc. You may want to install signal handlers to
manage this write-back.

File: make.info, Node: Terminal Output, Prev: Job Slots, Up: Integrating make
13.2 Synchronized Terminal Output
=================================
Normally GNU `make' will invoke all commands with access to the same
standard and error outputs that `make' itself was started with. A
number of tools will detect whether the output is a terminal or
not-a-terminal, and use this information to change the output style.
For example if the output goes to a terminal the tool may add control
characters that set color, or even change the location of the cursor.
If the output is not going to a terminal then these special control
characters are not emitted so that they don't corrupt log files, etc.
The `--output-sync' (*note Output During Parallel Output: Parallel
Output.) option will defeat the terminal detection. When output
synchronization is enabled GNU `make' arranges for all command output
to be written to a file, so that its output can be written as a block
without interference from other commands. This means that all tools
invoked by `make' will believe that their output is not going to be
displayed on a terminal, even when it will be (because `make' will
display it there after the command is completed).
In order to facilitate tools which would like to determine whether or
not their output will be displayed on a terminal, GNU `make' will set
the `MAKE_TERMOUT' and `MAKE_TERMERR' environment variables before
invoking any commands. Tools which would like to determine whether
standard or error output (respectively) will be displayed on a terminal
can check these environment variables to determine if they exist and
contain a non-empty value. If so the tool can assume that the output
will (eventually) be displayed on a terminal. If the variables are not
set or have an empty value, then the tool should fall back to its
normal methods of detecting whether output is going to a terminal or
not.
The content of the variables can be parsed to determine the type of
terminal which will be used to display the output.
Similarly, environments which invoke `make' and would like to
capture the output and eventually display it on a terminal (or some
display which can interpret terminal control characters) can set these
variables before invoking `make'. GNU `make' will not modify these
environment variables if they already exist when it starts.

File: make.info, Node: Features, Next: Missing, Prev: Integrating make, Up: Top
14 Features of GNU `make'
*************************
Here is a summary of the features of GNU `make', for comparison with
and credit to other versions of `make'. We consider the features of
`make' in 4.2 BSD systems as a baseline. If you are concerned with
writing portable makefiles, you should not use the features of `make'
listed here, nor the ones in *Note Missing::.
Many features come from the version of `make' in System V.
* The `VPATH' variable and its special meaning. *Note Searching
Directories for Prerequisites: Directory Search. This feature
exists in System V `make', but is undocumented. It is documented
in 4.3 BSD `make' (which says it mimics System V's `VPATH'
feature).
* Included makefiles. *Note Including Other Makefiles: Include.
Allowing multiple files to be included with a single directive is
a GNU extension.
* Variables are read from and communicated via the environment.
*Note Variables from the Environment: Environment.
* Options passed through the variable `MAKEFLAGS' to recursive
invocations of `make'. *Note Communicating Options to a
Sub-`make': Options/Recursion.
* The automatic variable `$%' is set to the member name in an
archive reference. *Note Automatic Variables::.
* The automatic variables `$@', `$*', `$<', `$%', and `$?' have
corresponding forms like `$(@F)' and `$(@D)'. We have generalized
this to `$^' as an obvious extension. *Note Automatic Variables::.
* Substitution variable references. *Note Basics of Variable
References: Reference.
* The command line options `-b' and `-m', accepted and ignored. In
System V `make', these options actually do something.
* Execution of recursive commands to run `make' via the variable
`MAKE' even if `-n', `-q' or `-t' is specified. *Note Recursive
Use of `make': Recursion.
* Support for suffix `.a' in suffix rules. *Note Archive Suffix
Rules::. This feature is obsolete in GNU `make', because the
general feature of rule chaining (*note Chains of Implicit Rules:
Chained Rules.) allows one pattern rule for installing members in
an archive (*note Archive Update::) to be sufficient.
* The arrangement of lines and backslash/newline combinations in
recipes is retained when the recipes are printed, so they appear as
they do in the makefile, except for the stripping of initial
whitespace.
The following features were inspired by various other versions of
`make'. In some cases it is unclear exactly which versions inspired
which others.
* Pattern rules using `%'. This has been implemented in several
versions of `make'. We're not sure who invented it first, but
it's been spread around a bit. *Note Defining and Redefining
Pattern Rules: Pattern Rules.
* Rule chaining and implicit intermediate files. This was
implemented by Stu Feldman in his version of `make' for AT&T
Eighth Edition Research Unix, and later by Andrew Hume of AT&T
Bell Labs in his `mk' program (where he terms it "transitive
closure"). We do not really know if we got this from either of
them or thought it up ourselves at the same time. *Note Chains of
Implicit Rules: Chained Rules.
* The automatic variable `$^' containing a list of all prerequisites
of the current target. We did not invent this, but we have no
idea who did. *Note Automatic Variables::. The automatic variable
`$+' is a simple extension of `$^'.
* The "what if" flag (`-W' in GNU `make') was (as far as we know)
invented by Andrew Hume in `mk'. *Note Instead of Executing
Recipes: Instead of Execution.
* The concept of doing several things at once (parallelism) exists in
many incarnations of `make' and similar programs, though not in the
System V or BSD implementations. *Note Recipe Execution:
Execution.
* A number of different build tools that support parallelism also
support collecting output and displaying as a single block. *Note
Output During Parallel Execution: Parallel Output.
* Modified variable references using pattern substitution come from
SunOS 4. *Note Basics of Variable References: Reference. This
functionality was provided in GNU `make' by the `patsubst'
function before the alternate syntax was implemented for
compatibility with SunOS 4. It is not altogether clear who
inspired whom, since GNU `make' had `patsubst' before SunOS 4 was
released.
* The special significance of `+' characters preceding recipe lines
(*note Instead of Executing Recipes: Instead of Execution.) is
mandated by `IEEE Standard 1003.2-1992' (POSIX.2).
* The `+=' syntax to append to the value of a variable comes from
SunOS 4 `make'. *Note Appending More Text to Variables: Appending.
* The syntax `ARCHIVE(MEM1 MEM2...)' to list multiple members in a
single archive file comes from SunOS 4 `make'. *Note Archive
Members::.
* The `-include' directive to include makefiles with no error for a
nonexistent file comes from SunOS 4 `make'. (But note that SunOS 4
`make' does not allow multiple makefiles to be specified in one
`-include' directive.) The same feature appears with the name
`sinclude' in SGI `make' and perhaps others.
* The `!=' shell assignment operator exists in many BSD of `make'
and is purposefully implemented here to behave identically to
those implementations.
* Various build management tools are implemented using scripting
languages such as Perl or Python and thus provide a natural
embedded scripting language, similar to GNU `make''s integration
of GNU Guile.
The remaining features are inventions new in GNU `make':
* Use the `-v' or `--version' option to print version and copyright
information.
* Use the `-h' or `--help' option to summarize the options to `make'.
* Simply-expanded variables. *Note The Two Flavors of Variables:
Flavors.
* Pass command line variable assignments automatically through the
variable `MAKE' to recursive `make' invocations. *Note Recursive
Use of `make': Recursion.
* Use the `-C' or `--directory' command option to change directory.
*Note Summary of Options: Options Summary.
* Make verbatim variable definitions with `define'. *Note Defining
Multi-Line Variables: Multi-Line.
* Declare phony targets with the special target `.PHONY'.
Andrew Hume of AT&T Bell Labs implemented a similar feature with a
different syntax in his `mk' program. This seems to be a case of
parallel discovery. *Note Phony Targets: Phony Targets.
* Manipulate text by calling functions. *Note Functions for
Transforming Text: Functions.
* Use the `-o' or `--old-file' option to pretend a file's
modification-time is old. *Note Avoiding Recompilation of Some
Files: Avoiding Compilation.
* Conditional execution.
This feature has been implemented numerous times in various
versions of `make'; it seems a natural extension derived from the
features of the C preprocessor and similar macro languages and is
not a revolutionary concept. *Note Conditional Parts of
Makefiles: Conditionals.
* Specify a search path for included makefiles. *Note Including
Other Makefiles: Include.
* Specify extra makefiles to read with an environment variable.
*Note The Variable `MAKEFILES': MAKEFILES Variable.
* Strip leading sequences of `./' from file names, so that `./FILE'
and `FILE' are considered to be the same file.
* Use a special search method for library prerequisites written in
the form `-lNAME'. *Note Directory Search for Link Libraries:
Libraries/Search.
* Allow suffixes for suffix rules (*note Old-Fashioned Suffix Rules:
Suffix Rules.) to contain any characters. In other versions of
`make', they must begin with `.' and not contain any `/'
characters.
* Keep track of the current level of `make' recursion using the
variable `MAKELEVEL'. *Note Recursive Use of `make': Recursion.
* Provide any goals given on the command line in the variable
`MAKECMDGOALS'. *Note Arguments to Specify the Goals: Goals.
* Specify static pattern rules. *Note Static Pattern Rules: Static
Pattern.
* Provide selective `vpath' search. *Note Searching Directories for
Prerequisites: Directory Search.
* Provide computed variable references. *Note Basics of Variable
References: Reference.
* Update makefiles. *Note How Makefiles Are Remade: Remaking
Makefiles. System V `make' has a very, very limited form of this
functionality in that it will check out SCCS files for makefiles.
* Various new built-in implicit rules. *Note Catalogue of Built-In
Rules: Catalogue of Rules.
* Load dynamic objects which can modify the behavior of `make'.
*Note Loading Dynamic Objects: Loading Objects.

File: make.info, Node: Missing, Next: Makefile Conventions, Prev: Features, Up: Top
15 Incompatibilities and Missing Features
*****************************************
The `make' programs in various other systems support a few features
that are not implemented in GNU `make'. The POSIX.2 standard (`IEEE
Standard 1003.2-1992') which specifies `make' does not require any of
these features.
* A target of the form `FILE((ENTRY))' stands for a member of
archive file FILE. The member is chosen, not by name, but by
being an object file which defines the linker symbol ENTRY.
This feature was not put into GNU `make' because of the
non-modularity of putting knowledge into `make' of the internal
format of archive file symbol tables. *Note Updating Archive
Symbol Directories: Archive Symbols.
* Suffixes (used in suffix rules) that end with the character `~'
have a special meaning to System V `make'; they refer to the SCCS
file that corresponds to the file one would get without the `~'.
For example, the suffix rule `.c~.o' would make the file `N.o' from
the SCCS file `s.N.c'. For complete coverage, a whole series of
such suffix rules is required. *Note Old-Fashioned Suffix Rules:
Suffix Rules.
In GNU `make', this entire series of cases is handled by two
pattern rules for extraction from SCCS, in combination with the
general feature of rule chaining. *Note Chains of Implicit Rules:
Chained Rules.
* In System V and 4.3 BSD `make', files found by `VPATH' search
(*note Searching Directories for Prerequisites: Directory Search.)
have their names changed inside recipes. We feel it is much
cleaner to always use automatic variables and thus make this
feature unnecessary.
* In some Unix `make's, the automatic variable `$*' appearing in the
prerequisites of a rule has the amazingly strange "feature" of
expanding to the full name of the _target of that rule_. We cannot
imagine what went on in the minds of Unix `make' developers to do
this; it is utterly inconsistent with the normal definition of
`$*'.
* In some Unix `make's, implicit rule search (*note Using Implicit
Rules: Implicit Rules.) is apparently done for _all_ targets, not
just those without recipes. This means you can do:
foo.o:
cc -c foo.c
and Unix `make' will intuit that `foo.o' depends on `foo.c'.
We feel that such usage is broken. The prerequisite properties of
`make' are well-defined (for GNU `make', at least), and doing such
a thing simply does not fit the model.
* GNU `make' does not include any built-in implicit rules for
compiling or preprocessing EFL programs. If we hear of anyone who
is using EFL, we will gladly add them.
* It appears that in SVR4 `make', a suffix rule can be specified
with no recipe, and it is treated as if it had an empty recipe
(*note Empty Recipes::). For example:
.c.a:
will override the built-in `.c.a' suffix rule.
We feel that it is cleaner for a rule without a recipe to always
simply add to the prerequisite list for the target. The above
example can be easily rewritten to get the desired behavior in GNU
`make':
.c.a: ;
* Some versions of `make' invoke the shell with the `-e' flag,
except under `-k' (*note Testing the Compilation of a Program:
Testing.). The `-e' flag tells the shell to exit as soon as any
program it runs returns a nonzero status. We feel it is cleaner to
write each line of the recipe to stand on its own and not require
this special treatment.

File: make.info, Node: Makefile Conventions, Next: Quick Reference, Prev: Missing, Up: Top
16 Makefile Conventions
***********************
This node describes conventions for writing the Makefiles for GNU
programs. Using Automake will help you write a Makefile that follows
these conventions. For more information on portable Makefiles, see
POSIX and *Note Portable Make Programming: (autoconf)Portable Make.
* Menu:
* Makefile Basics:: General conventions for Makefiles.
* Utilities in Makefiles:: Utilities to be used in Makefiles.
* Command Variables:: Variables for specifying commands.
* DESTDIR:: Supporting staged installs.
* Directory Variables:: Variables for installation directories.
* Standard Targets:: Standard targets for users.
* Install Command Categories:: Three categories of commands in the `install'
rule: normal, pre-install and post-install.

File: make.info, Node: Makefile Basics, Next: Utilities in Makefiles, Up: Makefile Conventions
16.1 General Conventions for Makefiles
======================================
Every Makefile should contain this line:
SHELL = /bin/sh
to avoid trouble on systems where the `SHELL' variable might be
inherited from the environment. (This is never a problem with GNU
`make'.)
Different `make' programs have incompatible suffix lists and
implicit rules, and this sometimes creates confusion or misbehavior. So
it is a good idea to set the suffix list explicitly using only the
suffixes you need in the particular Makefile, like this:
.SUFFIXES:
.SUFFIXES: .c .o
The first line clears out the suffix list, the second introduces all
suffixes which may be subject to implicit rules in this Makefile.
Don't assume that `.' is in the path for command execution. When
you need to run programs that are a part of your package during the
make, please make sure that it uses `./' if the program is built as
part of the make or `$(srcdir)/' if the file is an unchanging part of
the source code. Without one of these prefixes, the current search
path is used.
The distinction between `./' (the "build directory") and
`$(srcdir)/' (the "source directory") is important because users can
build in a separate directory using the `--srcdir' option to
`configure'. A rule of the form:
foo.1 : foo.man sedscript
sed -f sedscript foo.man > foo.1
will fail when the build directory is not the source directory, because
`foo.man' and `sedscript' are in the source directory.
When using GNU `make', relying on `VPATH' to find the source file
will work in the case where there is a single dependency file, since
the `make' automatic variable `$<' will represent the source file
wherever it is. (Many versions of `make' set `$<' only in implicit
rules.) A Makefile target like
foo.o : bar.c
$(CC) -I. -I$(srcdir) $(CFLAGS) -c bar.c -o foo.o
should instead be written as
foo.o : bar.c
$(CC) -I. -I$(srcdir) $(CFLAGS) -c $< -o $@
in order to allow `VPATH' to work correctly. When the target has
multiple dependencies, using an explicit `$(srcdir)' is the easiest way
to make the rule work well. For example, the target above for `foo.1'
is best written as:
foo.1 : foo.man sedscript
sed -f $(srcdir)/sedscript $(srcdir)/foo.man > $@
GNU distributions usually contain some files which are not source
files--for example, Info files, and the output from Autoconf, Automake,
Bison or Flex. Since these files normally appear in the source
directory, they should always appear in the source directory, not in the
build directory. So Makefile rules to update them should put the
updated files in the source directory.
However, if a file does not appear in the distribution, then the
Makefile should not put it in the source directory, because building a
program in ordinary circumstances should not modify the source directory
in any way.
Try to make the build and installation targets, at least (and all
their subtargets) work correctly with a parallel `make'.

File: make.info, Node: Utilities in Makefiles, Next: Command Variables, Prev: Makefile Basics, Up: Makefile Conventions
16.2 Utilities in Makefiles
===========================
Write the Makefile commands (and any shell scripts, such as
`configure') to run under `sh' (both the traditional Bourne shell and
the POSIX shell), not `csh'. Don't use any special features of `ksh'
or `bash', or POSIX features not widely supported in traditional Bourne
`sh'.
The `configure' script and the Makefile rules for building and
installation should not use any utilities directly except these:
awk cat cmp cp diff echo egrep expr false grep install-info ln ls
mkdir mv printf pwd rm rmdir sed sleep sort tar test touch tr true
Compression programs such as `gzip' can be used in the `dist' rule.
Generally, stick to the widely-supported (usually POSIX-specified)
options and features of these programs. For example, don't use `mkdir
-p', convenient as it may be, because a few systems don't support it at
all and with others, it is not safe for parallel execution. For a list
of known incompatibilities, see *Note Portable Shell Programming:
(autoconf)Portable Shell.
It is a good idea to avoid creating symbolic links in makefiles,
since a few file systems don't support them.
The Makefile rules for building and installation can also use
compilers and related programs, but should do so via `make' variables
so that the user can substitute alternatives. Here are some of the
programs we mean:
ar bison cc flex install ld ldconfig lex
make makeinfo ranlib texi2dvi yacc
Use the following `make' variables to run those programs:
$(AR) $(BISON) $(CC) $(FLEX) $(INSTALL) $(LD) $(LDCONFIG) $(LEX)
$(MAKE) $(MAKEINFO) $(RANLIB) $(TEXI2DVI) $(YACC)
When you use `ranlib' or `ldconfig', you should make sure nothing
bad happens if the system does not have the program in question.
Arrange to ignore an error from that command, and print a message before
the command to tell the user that failure of this command does not mean
a problem. (The Autoconf `AC_PROG_RANLIB' macro can help with this.)
If you use symbolic links, you should implement a fallback for
systems that don't have symbolic links.
Additional utilities that can be used via Make variables are:
chgrp chmod chown mknod
It is ok to use other utilities in Makefile portions (or scripts)
intended only for particular systems where you know those utilities
exist.

File: make.info, Node: Command Variables, Next: DESTDIR, Prev: Utilities in Makefiles, Up: Makefile Conventions
16.3 Variables for Specifying Commands
======================================
Makefiles should provide variables for overriding certain commands,
options, and so on.
In particular, you should run most utility programs via variables.
Thus, if you use Bison, have a variable named `BISON' whose default
value is set with `BISON = bison', and refer to it with `$(BISON)'
whenever you need to use Bison.
File management utilities such as `ln', `rm', `mv', and so on, need
not be referred to through variables in this way, since users don't
need to replace them with other programs.
Each program-name variable should come with an options variable that
is used to supply options to the program. Append `FLAGS' to the
program-name variable name to get the options variable name--for
example, `BISONFLAGS'. (The names `CFLAGS' for the C compiler,
`YFLAGS' for yacc, and `LFLAGS' for lex, are exceptions to this rule,
but we keep them because they are standard.) Use `CPPFLAGS' in any
compilation command that runs the preprocessor, and use `LDFLAGS' in
any compilation command that does linking as well as in any direct use
of `ld'.
If there are C compiler options that _must_ be used for proper
compilation of certain files, do not include them in `CFLAGS'. Users
expect to be able to specify `CFLAGS' freely themselves. Instead,
arrange to pass the necessary options to the C compiler independently
of `CFLAGS', by writing them explicitly in the compilation commands or
by defining an implicit rule, like this:
CFLAGS = -g
ALL_CFLAGS = -I. $(CFLAGS)
.c.o:
$(CC) -c $(CPPFLAGS) $(ALL_CFLAGS) $<
Do include the `-g' option in `CFLAGS', because that is not
_required_ for proper compilation. You can consider it a default that
is only recommended. If the package is set up so that it is compiled
with GCC by default, then you might as well include `-O' in the default
value of `CFLAGS' as well.
Put `CFLAGS' last in the compilation command, after other variables
containing compiler options, so the user can use `CFLAGS' to override
the others.
`CFLAGS' should be used in every invocation of the C compiler, both
those which do compilation and those which do linking.
Every Makefile should define the variable `INSTALL', which is the
basic command for installing a file into the system.
Every Makefile should also define the variables `INSTALL_PROGRAM'
and `INSTALL_DATA'. (The default for `INSTALL_PROGRAM' should be
`$(INSTALL)'; the default for `INSTALL_DATA' should be `${INSTALL} -m
644'.) Then it should use those variables as the commands for actual
installation, for executables and non-executables respectively.
Minimal use of these variables is as follows:
$(INSTALL_PROGRAM) foo $(bindir)/foo
$(INSTALL_DATA) libfoo.a $(libdir)/libfoo.a
However, it is preferable to support a `DESTDIR' prefix on the
target files, as explained in the next section.
It is acceptable, but not required, to install multiple files in one
command, with the final argument being a directory, as in:
$(INSTALL_PROGRAM) foo bar baz $(bindir)

File: make.info, Node: DESTDIR, Next: Directory Variables, Prev: Command Variables, Up: Makefile Conventions
16.4 `DESTDIR': Support for Staged Installs
===========================================
`DESTDIR' is a variable prepended to each installed target file, like
this:
$(INSTALL_PROGRAM) foo $(DESTDIR)$(bindir)/foo
$(INSTALL_DATA) libfoo.a $(DESTDIR)$(libdir)/libfoo.a
The `DESTDIR' variable is specified by the user on the `make'
command line as an absolute file name. For example:
make DESTDIR=/tmp/stage install
`DESTDIR' should be supported only in the `install*' and `uninstall*'
targets, as those are the only targets where it is useful.
If your installation step would normally install
`/usr/local/bin/foo' and `/usr/local/lib/libfoo.a', then an
installation invoked as in the example above would install
`/tmp/stage/usr/local/bin/foo' and `/tmp/stage/usr/local/lib/libfoo.a'
instead.
Prepending the variable `DESTDIR' to each target in this way
provides for "staged installs", where the installed files are not
placed directly into their expected location but are instead copied
into a temporary location (`DESTDIR'). However, installed files
maintain their relative directory structure and any embedded file names
will not be modified.
You should not set the value of `DESTDIR' in your `Makefile' at all;
then the files are installed into their expected locations by default.
Also, specifying `DESTDIR' should not change the operation of the
software in any way, so its value should not be included in any file
contents.
`DESTDIR' support is commonly used in package creation. It is also
helpful to users who want to understand what a given package will
install where, and to allow users who don't normally have permissions
to install into protected areas to build and install before gaining
those permissions. Finally, it can be useful with tools such as
`stow', where code is installed in one place but made to appear to be
installed somewhere else using symbolic links or special mount
operations. So, we strongly recommend GNU packages support `DESTDIR',
though it is not an absolute requirement.

File: make.info, Node: Directory Variables, Next: Standard Targets, Prev: DESTDIR, Up: Makefile Conventions
16.5 Variables for Installation Directories
===========================================
Installation directories should always be named by variables, so it is
easy to install in a nonstandard place. The standard names for these
variables and the values they should have in GNU packages are described
below. They are based on a standard file system layout; variants of it
are used in GNU/Linux and other modern operating systems.
Installers are expected to override these values when calling `make'
(e.g., `make prefix=/usr install') or `configure' (e.g., `configure
--prefix=/usr'). GNU packages should not try to guess which value
should be appropriate for these variables on the system they are being
installed onto: use the default settings specified here so that all GNU
packages behave identically, allowing the installer to achieve any
desired layout.
All installation directories, and their parent directories, should be
created (if necessary) before they are installed into.
These first two variables set the root for the installation. All the
other installation directories should be subdirectories of one of these
two, and nothing should be directly installed into these two
directories.
`prefix'
A prefix used in constructing the default values of the variables
listed below. The default value of `prefix' should be
`/usr/local'. When building the complete GNU system, the prefix
will be empty and `/usr' will be a symbolic link to `/'. (If you
are using Autoconf, write it as `@prefix@'.)
Running `make install' with a different value of `prefix' from the
one used to build the program should _not_ recompile the program.
`exec_prefix'
A prefix used in constructing the default values of some of the
variables listed below. The default value of `exec_prefix' should
be `$(prefix)'. (If you are using Autoconf, write it as
`@exec_prefix@'.)
Generally, `$(exec_prefix)' is used for directories that contain
machine-specific files (such as executables and subroutine
libraries), while `$(prefix)' is used directly for other
directories.
Running `make install' with a different value of `exec_prefix'
from the one used to build the program should _not_ recompile the
program.
Executable programs are installed in one of the following
directories.
`bindir'
The directory for installing executable programs that users can
run. This should normally be `/usr/local/bin', but write it as
`$(exec_prefix)/bin'. (If you are using Autoconf, write it as
`@bindir@'.)
`sbindir'
The directory for installing executable programs that can be run
from the shell, but are only generally useful to system
administrators. This should normally be `/usr/local/sbin', but
write it as `$(exec_prefix)/sbin'. (If you are using Autoconf,
write it as `@sbindir@'.)
`libexecdir'
The directory for installing executable programs to be run by other
programs rather than by users. This directory should normally be
`/usr/local/libexec', but write it as `$(exec_prefix)/libexec'.
(If you are using Autoconf, write it as `@libexecdir@'.)
The definition of `libexecdir' is the same for all packages, so
you should install your data in a subdirectory thereof. Most
packages install their data under `$(libexecdir)/PACKAGE-NAME/',
possibly within additional subdirectories thereof, such as
`$(libexecdir)/PACKAGE-NAME/MACHINE/VERSION'.
Data files used by the program during its execution are divided into
categories in two ways.
* Some files are normally modified by programs; others are never
normally modified (though users may edit some of these).
* Some files are architecture-independent and can be shared by all
machines at a site; some are architecture-dependent and can be
shared only by machines of the same kind and operating system;
others may never be shared between two machines.
This makes for six different possibilities. However, we want to
discourage the use of architecture-dependent files, aside from object
files and libraries. It is much cleaner to make other data files
architecture-independent, and it is generally not hard.
Here are the variables Makefiles should use to specify directories
to put these various kinds of files in:
`datarootdir'
The root of the directory tree for read-only
architecture-independent data files. This should normally be
`/usr/local/share', but write it as `$(prefix)/share'. (If you
are using Autoconf, write it as `@datarootdir@'.) `datadir''s
default value is based on this variable; so are `infodir',
`mandir', and others.
`datadir'
The directory for installing idiosyncratic read-only
architecture-independent data files for this program. This is
usually the same place as `datarootdir', but we use the two
separate variables so that you can move these program-specific
files without altering the location for Info files, man pages, etc.
This should normally be `/usr/local/share', but write it as
`$(datarootdir)'. (If you are using Autoconf, write it as
`@datadir@'.)
The definition of `datadir' is the same for all packages, so you
should install your data in a subdirectory thereof. Most packages
install their data under `$(datadir)/PACKAGE-NAME/'.
`sysconfdir'
The directory for installing read-only data files that pertain to a
single machine-that is to say, files for configuring a host.
Mailer and network configuration files, `/etc/passwd', and so
forth belong here. All the files in this directory should be
ordinary ASCII text files. This directory should normally be
`/usr/local/etc', but write it as `$(prefix)/etc'. (If you are
using Autoconf, write it as `@sysconfdir@'.)
Do not install executables here in this directory (they probably
belong in `$(libexecdir)' or `$(sbindir)'). Also do not install
files that are modified in the normal course of their use (programs
whose purpose is to change the configuration of the system
excluded). Those probably belong in `$(localstatedir)'.
`sharedstatedir'
The directory for installing architecture-independent data files
which the programs modify while they run. This should normally be
`/usr/local/com', but write it as `$(prefix)/com'. (If you are
using Autoconf, write it as `@sharedstatedir@'.)
`localstatedir'
The directory for installing data files which the programs modify
while they run, and that pertain to one specific machine. Users
should never need to modify files in this directory to configure
the package's operation; put such configuration information in
separate files that go in `$(datadir)' or `$(sysconfdir)'.
`$(localstatedir)' should normally be `/usr/local/var', but write
it as `$(prefix)/var'. (If you are using Autoconf, write it as
`@localstatedir@'.)
`runstatedir'
The directory for installing data files which the programs modify
while they run, that pertain to one specific machine, and which
need not persist longer than the execution of the program--which is
generally long-lived, for example, until the next reboot. PID
files for system daemons are a typical use. In addition, this
directory should not be cleaned except perhaps at reboot, while
the general `/tmp' (`TMPDIR') may be cleaned arbitrarily. This
should normally be `/var/run', but write it as
`$(localstatedir)/run'. Having it as a separate variable allows
the use of `/run' if desired, for example. (If you are using
Autoconf 2.70 or later, write it as `@runstatedir@'.)
These variables specify the directory for installing certain specific
types of files, if your program has them. Every GNU package should
have Info files, so every program needs `infodir', but not all need
`libdir' or `lispdir'.
`includedir'
The directory for installing header files to be included by user
programs with the C `#include' preprocessor directive. This
should normally be `/usr/local/include', but write it as
`$(prefix)/include'. (If you are using Autoconf, write it as
`@includedir@'.)
Most compilers other than GCC do not look for header files in
directory `/usr/local/include'. So installing the header files
this way is only useful with GCC. Sometimes this is not a problem
because some libraries are only really intended to work with GCC.
But some libraries are intended to work with other compilers.
They should install their header files in two places, one
specified by `includedir' and one specified by `oldincludedir'.
`oldincludedir'
The directory for installing `#include' header files for use with
compilers other than GCC. This should normally be `/usr/include'.
(If you are using Autoconf, you can write it as `@oldincludedir@'.)
The Makefile commands should check whether the value of
`oldincludedir' is empty. If it is, they should not try to use
it; they should cancel the second installation of the header files.
A package should not replace an existing header in this directory
unless the header came from the same package. Thus, if your Foo
package provides a header file `foo.h', then it should install the
header file in the `oldincludedir' directory if either (1) there
is no `foo.h' there or (2) the `foo.h' that exists came from the
Foo package.
To tell whether `foo.h' came from the Foo package, put a magic
string in the file--part of a comment--and `grep' for that string.
`docdir'
The directory for installing documentation files (other than Info)
for this package. By default, it should be
`/usr/local/share/doc/YOURPKG', but it should be written as
`$(datarootdir)/doc/YOURPKG'. (If you are using Autoconf, write
it as `@docdir@'.) The YOURPKG subdirectory, which may include a
version number, prevents collisions among files with common names,
such as `README'.
`infodir'
The directory for installing the Info files for this package. By
default, it should be `/usr/local/share/info', but it should be
written as `$(datarootdir)/info'. (If you are using Autoconf,
write it as `@infodir@'.) `infodir' is separate from `docdir' for
compatibility with existing practice.
`htmldir'
`dvidir'
`pdfdir'
`psdir'
Directories for installing documentation files in the particular
format. They should all be set to `$(docdir)' by default. (If
you are using Autoconf, write them as `@htmldir@', `@dvidir@',
etc.) Packages which supply several translations of their
documentation should install them in `$(htmldir)/'LL,
`$(pdfdir)/'LL, etc. where LL is a locale abbreviation such as
`en' or `pt_BR'.
`libdir'
The directory for object files and libraries of object code. Do
not install executables here, they probably ought to go in
`$(libexecdir)' instead. The value of `libdir' should normally be
`/usr/local/lib', but write it as `$(exec_prefix)/lib'. (If you
are using Autoconf, write it as `@libdir@'.)
`lispdir'
The directory for installing any Emacs Lisp files in this package.
By default, it should be `/usr/local/share/emacs/site-lisp', but
it should be written as `$(datarootdir)/emacs/site-lisp'.
If you are using Autoconf, write the default as `@lispdir@'. In
order to make `@lispdir@' work, you need the following lines in
your `configure.ac' file:
lispdir='${datarootdir}/emacs/site-lisp'
AC_SUBST(lispdir)
`localedir'
The directory for installing locale-specific message catalogs for
this package. By default, it should be `/usr/local/share/locale',
but it should be written as `$(datarootdir)/locale'. (If you are
using Autoconf, write it as `@localedir@'.) This directory
usually has a subdirectory per locale.
Unix-style man pages are installed in one of the following:
`mandir'
The top-level directory for installing the man pages (if any) for
this package. It will normally be `/usr/local/share/man', but you
should write it as `$(datarootdir)/man'. (If you are using
Autoconf, write it as `@mandir@'.)
`man1dir'
The directory for installing section 1 man pages. Write it as
`$(mandir)/man1'.
`man2dir'
The directory for installing section 2 man pages. Write it as
`$(mandir)/man2'
`...'
*Don't make the primary documentation for any GNU software be a
man page. Write a manual in Texinfo instead. Man pages are just
for the sake of people running GNU software on Unix, which is a
secondary application only.*
`manext'
The file name extension for the installed man page. This should
contain a period followed by the appropriate digit; it should
normally be `.1'.
`man1ext'
The file name extension for installed section 1 man pages.
`man2ext'
The file name extension for installed section 2 man pages.
`...'
Use these names instead of `manext' if the package needs to
install man pages in more than one section of the manual.
And finally, you should set the following variable:
`srcdir'
The directory for the sources being compiled. The value of this
variable is normally inserted by the `configure' shell script.
(If you are using Autoconf, use `srcdir = @srcdir@'.)
For example:
# Common prefix for installation directories.
# NOTE: This directory must exist when you start the install.
prefix = /usr/local
datarootdir = $(prefix)/share
datadir = $(datarootdir)
exec_prefix = $(prefix)
# Where to put the executable for the command 'gcc'.
bindir = $(exec_prefix)/bin
# Where to put the directories used by the compiler.
libexecdir = $(exec_prefix)/libexec
# Where to put the Info files.
infodir = $(datarootdir)/info
If your program installs a large number of files into one of the
standard user-specified directories, it might be useful to group them
into a subdirectory particular to that program. If you do this, you
should write the `install' rule to create these subdirectories.
Do not expect the user to include the subdirectory name in the value
of any of the variables listed above. The idea of having a uniform set
of variable names for installation directories is to enable the user to
specify the exact same values for several different GNU packages. In
order for this to be useful, all the packages must be designed so that
they will work sensibly when the user does so.
At times, not all of these variables may be implemented in the
current release of Autoconf and/or Automake; but as of Autoconf 2.60, we
believe all of them are. When any are missing, the descriptions here
serve as specifications for what Autoconf will implement. As a
programmer, you can either use a development version of Autoconf or
avoid using these variables until a stable release is made which
supports them.

File: make.info, Node: Standard Targets, Next: Install Command Categories, Prev: Directory Variables, Up: Makefile Conventions
16.6 Standard Targets for Users
===============================
All GNU programs should have the following targets in their Makefiles:
`all'
Compile the entire program. This should be the default target.
This target need not rebuild any documentation files; Info files
should normally be included in the distribution, and DVI (and other
documentation format) files should be made only when explicitly
asked for.
By default, the Make rules should compile and link with `-g', so
that executable programs have debugging symbols. Otherwise, you
are essentially helpless in the face of a crash, and it is often
far from easy to reproduce with a fresh build.
`install'
Compile the program and copy the executables, libraries, and so on
to the file names where they should reside for actual use. If
there is a simple test to verify that a program is properly
installed, this target should run that test.
Do not strip executables when installing them. This helps eventual
debugging that may be needed later, and nowadays disk space is
cheap and dynamic loaders typically ensure debug sections are not
loaded during normal execution. Users that need stripped binaries
may invoke the `install-strip' target to do that.
If possible, write the `install' target rule so that it does not
modify anything in the directory where the program was built,
provided `make all' has just been done. This is convenient for
building the program under one user name and installing it under
another.
The commands should create all the directories in which files are
to be installed, if they don't already exist. This includes the
directories specified as the values of the variables `prefix' and
`exec_prefix', as well as all subdirectories that are needed. One
way to do this is by means of an `installdirs' target as described
below.
Use `-' before any command for installing a man page, so that
`make' will ignore any errors. This is in case there are systems
that don't have the Unix man page documentation system installed.
The way to install Info files is to copy them into `$(infodir)'
with `$(INSTALL_DATA)' (*note Command Variables::), and then run
the `install-info' program if it is present. `install-info' is a
program that edits the Info `dir' file to add or update the menu
entry for the given Info file; it is part of the Texinfo package.
Here is a sample rule to install an Info file that also tries to
handle some additional situations, such as `install-info' not
being present.
do-install-info: foo.info installdirs
$(NORMAL_INSTALL)
# Prefer an info file in . to one in srcdir.
if test -f foo.info; then d=.; \
else d="$(srcdir)"; fi; \
$(INSTALL_DATA) $$d/foo.info \
"$(DESTDIR)$(infodir)/foo.info"
# Run install-info only if it exists.
# Use 'if' instead of just prepending '-' to the
# line so we notice real errors from install-info.
# Use '$(SHELL) -c' because some shells do not
# fail gracefully when there is an unknown command.
$(POST_INSTALL)
if $(SHELL) -c 'install-info --version' \
>/dev/null 2>&1; then \
install-info --dir-file="$(DESTDIR)$(infodir)/dir" \
"$(DESTDIR)$(infodir)/foo.info"; \
else true; fi
When writing the `install' target, you must classify all the
commands into three categories: normal ones, "pre-installation"
commands and "post-installation" commands. *Note Install Command
Categories::.
`install-html'
`install-dvi'
`install-pdf'
`install-ps'
These targets install documentation in formats other than Info;
they're intended to be called explicitly by the person installing
the package, if that format is desired. GNU prefers Info files,
so these must be installed by the `install' target.
When you have many documentation files to install, we recommend
that you avoid collisions and clutter by arranging for these
targets to install in subdirectories of the appropriate
installation directory, such as `htmldir'. As one example, if
your package has multiple manuals, and you wish to install HTML
documentation with many files (such as the "split" mode output by
`makeinfo --html'), you'll certainly want to use subdirectories,
or two nodes with the same name in different manuals will
overwrite each other.
Please make these `install-FORMAT' targets invoke the commands for
the FORMAT target, for example, by making FORMAT a dependency.
`uninstall'
Delete all the installed files--the copies that the `install' and
`install-*' targets create.
This rule should not modify the directories where compilation is
done, only the directories where files are installed.
The uninstallation commands are divided into three categories,
just like the installation commands. *Note Install Command
Categories::.
`install-strip'
Like `install', but strip the executable files while installing
them. In simple cases, this target can use the `install' target in
a simple way:
install-strip:
$(MAKE) INSTALL_PROGRAM='$(INSTALL_PROGRAM) -s' \
install
But if the package installs scripts as well as real executables,
the `install-strip' target can't just refer to the `install'
target; it has to strip the executables but not the scripts.
`install-strip' should not strip the executables in the build
directory which are being copied for installation. It should only
strip the copies that are installed.
Normally we do not recommend stripping an executable unless you
are sure the program has no bugs. However, it can be reasonable
to install a stripped executable for actual execution while saving
the unstripped executable elsewhere in case there is a bug.
`clean'
Delete all files in the current directory that are normally
created by building the program. Also delete files in other
directories if they are created by this makefile. However, don't
delete the files that record the configuration. Also preserve
files that could be made by building, but normally aren't because
the distribution comes with them. There is no need to delete
parent directories that were created with `mkdir -p', since they
could have existed anyway.
Delete `.dvi' files here if they are not part of the distribution.
`distclean'
Delete all files in the current directory (or created by this
makefile) that are created by configuring or building the program.
If you have unpacked the source and built the program without
creating any other files, `make distclean' should leave only the
files that were in the distribution. However, there is no need to
delete parent directories that were created with `mkdir -p', since
they could have existed anyway.
`mostlyclean'
Like `clean', but may refrain from deleting a few files that people
normally don't want to recompile. For example, the `mostlyclean'
target for GCC does not delete `libgcc.a', because recompiling it
is rarely necessary and takes a lot of time.
`maintainer-clean'
Delete almost everything that can be reconstructed with this
Makefile. This typically includes everything deleted by
`distclean', plus more: C source files produced by Bison, tags
tables, Info files, and so on.
The reason we say "almost everything" is that running the command
`make maintainer-clean' should not delete `configure' even if
`configure' can be remade using a rule in the Makefile. More
generally, `make maintainer-clean' should not delete anything that
needs to exist in order to run `configure' and then begin to build
the program. Also, there is no need to delete parent directories
that were created with `mkdir -p', since they could have existed
anyway. These are the only exceptions; `maintainer-clean' should
delete everything else that can be rebuilt.
The `maintainer-clean' target is intended to be used by a
maintainer of the package, not by ordinary users. You may need
special tools to reconstruct some of the files that `make
maintainer-clean' deletes. Since these files are normally
included in the distribution, we don't take care to make them easy
to reconstruct. If you find you need to unpack the full
distribution again, don't blame us.
To help make users aware of this, the commands for the special
`maintainer-clean' target should start with these two:
@echo 'This command is intended for maintainers to use; it'
@echo 'deletes files that may need special tools to rebuild.'
`TAGS'
Update a tags table for this program.
`info'
Generate any Info files needed. The best way to write the rules
is as follows:
info: foo.info
foo.info: foo.texi chap1.texi chap2.texi
$(MAKEINFO) $(srcdir)/foo.texi
You must define the variable `MAKEINFO' in the Makefile. It should
run the `makeinfo' program, which is part of the Texinfo
distribution.
Normally a GNU distribution comes with Info files, and that means
the Info files are present in the source directory. Therefore,
the Make rule for an info file should update it in the source
directory. When users build the package, ordinarily Make will not
update the Info files because they will already be up to date.
`dvi'
`html'
`pdf'
`ps'
Generate documentation files in the given format. These targets
should always exist, but any or all can be a no-op if the given
output format cannot be generated. These targets should not be
dependencies of the `all' target; the user must manually invoke
them.
Here's an example rule for generating DVI files from Texinfo:
dvi: foo.dvi
foo.dvi: foo.texi chap1.texi chap2.texi
$(TEXI2DVI) $(srcdir)/foo.texi
You must define the variable `TEXI2DVI' in the Makefile. It
should run the program `texi2dvi', which is part of the Texinfo
distribution. (`texi2dvi' uses TeX to do the real work of
formatting. TeX is not distributed with Texinfo.) Alternatively,
write only the dependencies, and allow GNU `make' to provide the
command.
Here's another example, this one for generating HTML from Texinfo:
html: foo.html
foo.html: foo.texi chap1.texi chap2.texi
$(TEXI2HTML) $(srcdir)/foo.texi
Again, you would define the variable `TEXI2HTML' in the Makefile;
for example, it might run `makeinfo --no-split --html' (`makeinfo'
is part of the Texinfo distribution).
`dist'
Create a distribution tar file for this program. The tar file
should be set up so that the file names in the tar file start with
a subdirectory name which is the name of the package it is a
distribution for. This name can include the version number.
For example, the distribution tar file of GCC version 1.40 unpacks
into a subdirectory named `gcc-1.40'.
The easiest way to do this is to create a subdirectory
appropriately named, use `ln' or `cp' to install the proper files
in it, and then `tar' that subdirectory.
Compress the tar file with `gzip'. For example, the actual
distribution file for GCC version 1.40 is called `gcc-1.40.tar.gz'.
It is ok to support other free compression formats as well.
The `dist' target should explicitly depend on all non-source files
that are in the distribution, to make sure they are up to date in
the distribution. *Note Making Releases: (standards)Releases.
`check'
Perform self-tests (if any). The user must build the program
before running the tests, but need not install the program; you
should write the self-tests so that they work when the program is
built but not installed.
The following targets are suggested as conventional names, for
programs in which they are useful.
`installcheck'
Perform installation tests (if any). The user must build and
install the program before running the tests. You should not
assume that `$(bindir)' is in the search path.
`installdirs'
It's useful to add a target named `installdirs' to create the
directories where files are installed, and their parent
directories. There is a script called `mkinstalldirs' which is
convenient for this; you can find it in the Gnulib package. You
can use a rule like this:
# Make sure all installation directories (e.g. $(bindir))
# actually exist by making them if necessary.
installdirs: mkinstalldirs
$(srcdir)/mkinstalldirs $(bindir) $(datadir) \
$(libdir) $(infodir) \
$(mandir)
or, if you wish to support `DESTDIR' (strongly encouraged),
# Make sure all installation directories (e.g. $(bindir))
# actually exist by making them if necessary.
installdirs: mkinstalldirs
$(srcdir)/mkinstalldirs \
$(DESTDIR)$(bindir) $(DESTDIR)$(datadir) \
$(DESTDIR)$(libdir) $(DESTDIR)$(infodir) \
$(DESTDIR)$(mandir)
This rule should not modify the directories where compilation is
done. It should do nothing but create installation directories.

File: make.info, Node: Install Command Categories, Prev: Standard Targets, Up: Makefile Conventions
16.7 Install Command Categories
===============================
When writing the `install' target, you must classify all the commands
into three categories: normal ones, "pre-installation" commands and
"post-installation" commands.
Normal commands move files into their proper places, and set their
modes. They may not alter any files except the ones that come entirely
from the package they belong to.
Pre-installation and post-installation commands may alter other
files; in particular, they can edit global configuration files or data
bases.
Pre-installation commands are typically executed before the normal
commands, and post-installation commands are typically run after the
normal commands.
The most common use for a post-installation command is to run
`install-info'. This cannot be done with a normal command, since it
alters a file (the Info directory) which does not come entirely and
solely from the package being installed. It is a post-installation
command because it needs to be done after the normal command which
installs the package's Info files.
Most programs don't need any pre-installation commands, but we have
the feature just in case it is needed.
To classify the commands in the `install' rule into these three
categories, insert "category lines" among them. A category line
specifies the category for the commands that follow.
A category line consists of a tab and a reference to a special Make
variable, plus an optional comment at the end. There are three
variables you can use, one for each category; the variable name
specifies the category. Category lines are no-ops in ordinary execution
because these three Make variables are normally undefined (and you
_should not_ define them in the makefile).
Here are the three possible category lines, each with a comment that
explains what it means:
$(PRE_INSTALL) # Pre-install commands follow.
$(POST_INSTALL) # Post-install commands follow.
$(NORMAL_INSTALL) # Normal commands follow.
If you don't use a category line at the beginning of the `install'
rule, all the commands are classified as normal until the first category
line. If you don't use any category lines, all the commands are
classified as normal.
These are the category lines for `uninstall':
$(PRE_UNINSTALL) # Pre-uninstall commands follow.
$(POST_UNINSTALL) # Post-uninstall commands follow.
$(NORMAL_UNINSTALL) # Normal commands follow.
Typically, a pre-uninstall command would be used for deleting entries
from the Info directory.
If the `install' or `uninstall' target has any dependencies which
act as subroutines of installation, then you should start _each_
dependency's commands with a category line, and start the main target's
commands with a category line also. This way, you can ensure that each
command is placed in the right category regardless of which of the
dependencies actually run.
Pre-installation and post-installation commands should not run any
programs except for these:
[ basename bash cat chgrp chmod chown cmp cp dd diff echo
egrep expand expr false fgrep find getopt grep gunzip gzip
hostname install install-info kill ldconfig ln ls md5sum
mkdir mkfifo mknod mv printenv pwd rm rmdir sed sort tee
test touch true uname xargs yes
The reason for distinguishing the commands in this way is for the
sake of making binary packages. Typically a binary package contains
all the executables and other files that need to be installed, and has
its own method of installing them--so it does not need to run the normal
installation commands. But installing the binary package does need to
execute the pre-installation and post-installation commands.
Programs to build binary packages work by extracting the
pre-installation and post-installation commands. Here is one way of
extracting the pre-installation commands (the `-s' option to `make' is
needed to silence messages about entering subdirectories):
make -s -n install -o all \
PRE_INSTALL=pre-install \
POST_INSTALL=post-install \
NORMAL_INSTALL=normal-install \
| gawk -f pre-install.awk
where the file `pre-install.awk' could contain this:
$0 ~ /^(normal-install|post-install)[ \t]*$/ {on = 0}
on {print $0}
$0 ~ /^pre-install[ \t]*$/ {on = 1}

File: make.info, Node: Quick Reference, Next: Error Messages, Prev: Makefile Conventions, Up: Top
Appendix A Quick Reference
**************************
This appendix summarizes the directives, text manipulation functions,
and special variables which GNU `make' understands. *Note Special
Targets::, *Note Catalogue of Built-In Rules: Catalogue of Rules, and
*Note Summary of Options: Options Summary, for other summaries.
Here is a summary of the directives GNU `make' recognizes:
`define VARIABLE'
`define VARIABLE ='
`define VARIABLE :='
`define VARIABLE ::='
`define VARIABLE +='
`define VARIABLE ?='
`endef'
Define multi-line variables.
*Note Multi-Line::.
`undefine VARIABLE'
Undefining variables.
*Note Undefine Directive::.
`ifdef VARIABLE'
`ifndef VARIABLE'
`ifeq (A,B)'
`ifeq "A" "B"'
`ifeq 'A' 'B''
`ifneq (A,B)'
`ifneq "A" "B"'
`ifneq 'A' 'B''
`else'
`endif'
Conditionally evaluate part of the makefile.
*Note Conditionals::.
`include FILE'
`-include FILE'
`sinclude FILE'
Include another makefile.
*Note Including Other Makefiles: Include.
`override VARIABLE-ASSIGNMENT'
Define a variable, overriding any previous definition, even one
from the command line.
*Note The `override' Directive: Override Directive.
`export'
Tell `make' to export all variables to child processes by default.
*Note Communicating Variables to a Sub-`make': Variables/Recursion.
`export VARIABLE'
`export VARIABLE-ASSIGNMENT'
`unexport VARIABLE'
Tell `make' whether or not to export a particular variable to child
processes.
*Note Communicating Variables to a Sub-`make': Variables/Recursion.
`private VARIABLE-ASSIGNMENT'
Do not allow this variable assignment to be inherited by
prerequisites.
*Note Suppressing Inheritance::.
`vpath PATTERN PATH'
Specify a search path for files matching a `%' pattern.
*Note The `vpath' Directive: Selective Search.
`vpath PATTERN'
Remove all search paths previously specified for PATTERN.
`vpath'
Remove all search paths previously specified in any `vpath'
directive.
Here is a summary of the built-in functions (*note Functions::):
`$(subst FROM,TO,TEXT)'
Replace FROM with TO in TEXT.
*Note Functions for String Substitution and Analysis: Text
Functions.
`$(patsubst PATTERN,REPLACEMENT,TEXT)'
Replace words matching PATTERN with REPLACEMENT in TEXT.
*Note Functions for String Substitution and Analysis: Text
Functions.
`$(strip STRING)'
Remove excess whitespace characters from STRING.
*Note Functions for String Substitution and Analysis: Text
Functions.
`$(findstring FIND,TEXT)'
Locate FIND in TEXT.
*Note Functions for String Substitution and Analysis: Text
Functions.
`$(filter PATTERN...,TEXT)'
Select words in TEXT that match one of the PATTERN words.
*Note Functions for String Substitution and Analysis: Text
Functions.
`$(filter-out PATTERN...,TEXT)'
Select words in TEXT that _do not_ match any of the PATTERN words.
*Note Functions for String Substitution and Analysis: Text
Functions.
`$(sort LIST)'
Sort the words in LIST lexicographically, removing duplicates.
*Note Functions for String Substitution and Analysis: Text
Functions.
`$(word N,TEXT)'
Extract the Nth word (one-origin) of TEXT.
*Note Functions for String Substitution and Analysis: Text
Functions.
`$(words TEXT)'
Count the number of words in TEXT.
*Note Functions for String Substitution and Analysis: Text
Functions.
`$(wordlist S,E,TEXT)'
Returns the list of words in TEXT from S to E.
*Note Functions for String Substitution and Analysis: Text
Functions.
`$(firstword NAMES...)'
Extract the first word of NAMES.
*Note Functions for String Substitution and Analysis: Text
Functions.
`$(lastword NAMES...)'
Extract the last word of NAMES.
*Note Functions for String Substitution and Analysis: Text
Functions.
`$(dir NAMES...)'
Extract the directory part of each file name.
*Note Functions for File Names: File Name Functions.
`$(notdir NAMES...)'
Extract the non-directory part of each file name.
*Note Functions for File Names: File Name Functions.
`$(suffix NAMES...)'
Extract the suffix (the last `.' and following characters) of each
file name.
*Note Functions for File Names: File Name Functions.
`$(basename NAMES...)'
Extract the base name (name without suffix) of each file name.
*Note Functions for File Names: File Name Functions.
`$(addsuffix SUFFIX,NAMES...)'
Append SUFFIX to each word in NAMES.
*Note Functions for File Names: File Name Functions.
`$(addprefix PREFIX,NAMES...)'
Prepend PREFIX to each word in NAMES.
*Note Functions for File Names: File Name Functions.
`$(join LIST1,LIST2)'
Join two parallel lists of words.
*Note Functions for File Names: File Name Functions.
`$(wildcard PATTERN...)'
Find file names matching a shell file name pattern (_not_ a `%'
pattern).
*Note The Function `wildcard': Wildcard Function.
`$(realpath NAMES...)'
For each file name in NAMES, expand to an absolute name that does
not contain any `.', `..', nor symlinks.
*Note Functions for File Names: File Name Functions.
`$(abspath NAMES...)'
For each file name in NAMES, expand to an absolute name that does
not contain any `.' or `..' components, but preserves symlinks.
*Note Functions for File Names: File Name Functions.
`$(error TEXT...)'
When this function is evaluated, `make' generates a fatal error
with the message TEXT.
*Note Functions That Control Make: Make Control Functions.
`$(warning TEXT...)'
When this function is evaluated, `make' generates a warning with
the message TEXT.
*Note Functions That Control Make: Make Control Functions.
`$(shell COMMAND)'
Execute a shell command and return its output.
*Note The `shell' Function: Shell Function.
`$(origin VARIABLE)'
Return a string describing how the `make' variable VARIABLE was
defined.
*Note The `origin' Function: Origin Function.
`$(flavor VARIABLE)'
Return a string describing the flavor of the `make' variable
VARIABLE.
*Note The `flavor' Function: Flavor Function.
`$(foreach VAR,WORDS,TEXT)'
Evaluate TEXT with VAR bound to each word in WORDS, and
concatenate the results.
*Note The `foreach' Function: Foreach Function.
`$(if CONDITION,THEN-PART[,ELSE-PART])'
Evaluate the condition CONDITION; if it's non-empty substitute the
expansion of the THEN-PART otherwise substitute the expansion of
the ELSE-PART.
*Note Functions for Conditionals: Conditional Functions.
`$(or CONDITION1[,CONDITION2[,CONDITION3...]])'
Evaluate each condition CONDITIONN one at a time; substitute the
first non-empty expansion. If all expansions are empty, substitute
the empty string.
*Note Functions for Conditionals: Conditional Functions.
`$(and CONDITION1[,CONDITION2[,CONDITION3...]])'
Evaluate each condition CONDITIONN one at a time; if any expansion
results in the empty string substitute the empty string. If all
expansions result in a non-empty string, substitute the expansion
of the last CONDITION.
*Note Functions for Conditionals: Conditional Functions.
`$(call VAR,PARAM,...)'
Evaluate the variable VAR replacing any references to `$(1)',
`$(2)' with the first, second, etc. PARAM values.
*Note The `call' Function: Call Function.
`$(eval TEXT)'
Evaluate TEXT then read the results as makefile commands. Expands
to the empty string.
*Note The `eval' Function: Eval Function.
`$(file OP FILENAME,TEXT)'
Expand the arguments, then open the file FILENAME using mode OP
and write TEXT to that file.
*Note The `file' Function: File Function.
`$(value VAR)'
Evaluates to the contents of the variable VAR, with no expansion
performed on it.
*Note The `value' Function: Value Function.
Here is a summary of the automatic variables. *Note Automatic
Variables::, for full information.
`$@'
The file name of the target.
`$%'
The target member name, when the target is an archive member.
`$<'
The name of the first prerequisite.
`$?'
The names of all the prerequisites that are newer than the target,
with spaces between them. For prerequisites which are archive
members, only the named member is used (*note Archives::).
`$^'
`$+'
The names of all the prerequisites, with spaces between them. For
prerequisites which are archive members, only the named member is
used (*note Archives::). The value of `$^' omits duplicate
prerequisites, while `$+' retains them and preserves their order.
`$*'
The stem with which an implicit rule matches (*note How Patterns
Match: Pattern Match.).
`$(@D)'
`$(@F)'
The directory part and the file-within-directory part of `$@'.
`$(*D)'
`$(*F)'
The directory part and the file-within-directory part of `$*'.
`$(%D)'
`$(%F)'
The directory part and the file-within-directory part of `$%'.
`$(<D)'
`$(<F)'
The directory part and the file-within-directory part of `$<'.
`$(^D)'
`$(^F)'
The directory part and the file-within-directory part of `$^'.
`$(+D)'
`$(+F)'
The directory part and the file-within-directory part of `$+'.
`$(?D)'
`$(?F)'
The directory part and the file-within-directory part of `$?'.
These variables are used specially by GNU `make':
`MAKEFILES'
Makefiles to be read on every invocation of `make'.
*Note The Variable `MAKEFILES': MAKEFILES Variable.
`VPATH'
Directory search path for files not found in the current directory.
*Note `VPATH' Search Path for All Prerequisites: General Search.
`SHELL'
The name of the system default command interpreter, usually
`/bin/sh'. You can set `SHELL' in the makefile to change the
shell used to run recipes. *Note Recipe Execution: Execution.
The `SHELL' variable is handled specially when importing from and
exporting to the environment. *Note Choosing the Shell::.
`MAKESHELL'
On MS-DOS only, the name of the command interpreter that is to be
used by `make'. This value takes precedence over the value of
`SHELL'. *Note MAKESHELL variable: Execution.
`MAKE'
The name with which `make' was invoked. Using this variable in
recipes has special meaning. *Note How the `MAKE' Variable Works:
MAKE Variable.
`MAKE_VERSION'
The built-in variable `MAKE_VERSION' expands to the version number
of the GNU `make' program.
`MAKE_HOST'
The built-in variable `MAKE_HOST' expands to a string representing
the host that GNU `make' was built to run on.
`MAKELEVEL'
The number of levels of recursion (sub-`make's).
*Note Variables/Recursion::.
`MAKEFLAGS'
The flags given to `make'. You can set this in the environment or
a makefile to set flags.
*Note Communicating Options to a Sub-`make': Options/Recursion.
It is _never_ appropriate to use `MAKEFLAGS' directly in a recipe
line: its contents may not be quoted correctly for use in the
shell. Always allow recursive `make''s to obtain these values
through the environment from its parent.
`GNUMAKEFLAGS'
Other flags parsed by `make'. You can set this in the environment
or a makefile to set `make' command-line flags. GNU `make' never
sets this variable itself. This variable is only needed if you'd
like to set GNU `make'-specific flags in a POSIX-compliant
makefile. This variable will be seen by GNU `make' and ignored by
other `make' implementations. It's not needed if you only use GNU
`make'; just use `MAKEFLAGS' directly. *Note Communicating
Options to a Sub-`make': Options/Recursion.
`MAKECMDGOALS'
The targets given to `make' on the command line. Setting this
variable has no effect on the operation of `make'.
*Note Arguments to Specify the Goals: Goals.
`CURDIR'
Set to the absolute pathname of the current working directory
(after all `-C' options are processed, if any). Setting this
variable has no effect on the operation of `make'.
*Note Recursive Use of `make': Recursion.
`SUFFIXES'
The default list of suffixes before `make' reads any makefiles.
`.LIBPATTERNS'
Defines the naming of the libraries `make' searches for, and their
order.
*Note Directory Search for Link Libraries: Libraries/Search.

File: make.info, Node: Error Messages, Next: Complex Makefile, Prev: Quick Reference, Up: Top
Appendix B Errors Generated by Make
***********************************
Here is a list of the more common errors you might see generated by
`make', and some information about what they mean and how to fix them.
Sometimes `make' errors are not fatal, especially in the presence of
a `-' prefix on a recipe line, or the `-k' command line option. Errors
that are fatal are prefixed with the string `***'.
Error messages are all either prefixed with the name of the program
(usually `make'), or, if the error is found in a makefile, the name of
the file and line number containing the problem.
In the table below, these common prefixes are left off.
`[FOO] Error NN'
`[FOO] SIGNAL DESCRIPTION'
These errors are not really `make' errors at all. They mean that a
program that `make' invoked as part of a recipe returned a non-0
error code (`Error NN'), which `make' interprets as failure, or it
exited in some other abnormal fashion (with a signal of some
type). *Note Errors in Recipes: Errors.
If no `***' is attached to the message, then the sub-process failed
but the rule in the makefile was prefixed with the `-' special
character, so `make' ignored the error.
`missing separator. Stop.'
`missing separator (did you mean TAB instead of 8 spaces?). Stop.'
This means that `make' could not understand much of anything about
the makefile line it just read. GNU `make' looks for various
separators (`:', `=', recipe prefix characters, etc.) to indicate
what kind of line it's parsing. This message means it couldn't
find a valid one.
One of the most common reasons for this message is that you (or
perhaps your oh-so-helpful editor, as is the case with many
MS-Windows editors) have attempted to indent your recipe lines
with spaces instead of a tab character. In this case, `make' will
use the second form of the error above. Remember that every line
in the recipe must begin with a tab character (unless you set
`.RECIPEPREFIX'; *note Special Variables::). Eight spaces do not
count. *Note Rule Syntax::.
`recipe commences before first target. Stop.'
`missing rule before recipe. Stop.'
This means the first thing in the makefile seems to be part of a
recipe: it begins with a recipe prefix character and doesn't
appear to be a legal `make' directive (such as a variable
assignment). Recipes must always be associated with a target.
The second form is generated if the line has a semicolon as the
first non-whitespace character; `make' interprets this to mean you
left out the "target: prerequisite" section of a rule. *Note Rule
Syntax::.
`No rule to make target `XXX'.'
`No rule to make target `XXX', needed by `YYY'.'
This means that `make' decided it needed to build a target, but
then couldn't find any instructions in the makefile on how to do
that, either explicit or implicit (including in the default rules
database).
If you want that file to be built, you will need to add a rule to
your makefile describing how that target can be built. Other
possible sources of this problem are typos in the makefile (if
that file name is wrong) or a corrupted source tree (if that file
is not supposed to be built, but rather only a prerequisite).
`No targets specified and no makefile found. Stop.'
`No targets. Stop.'
The former means that you didn't provide any targets to be built
on the command line, and `make' couldn't find any makefiles to
read in. The latter means that some makefile was found, but it
didn't contain any default goal and none was given on the command
line. GNU `make' has nothing to do in these situations. *Note
Arguments to Specify the Makefile: Makefile Arguments.
`Makefile `XXX' was not found.'
`Included makefile `XXX' was not found.'
A makefile specified on the command line (first form) or included
(second form) was not found.
`warning: overriding recipe for target `XXX''
`warning: ignoring old recipe for target `XXX''
GNU `make' allows only one recipe to be specified per target
(except for double-colon rules). If you give a recipe for a target
which already has been defined to have one, this warning is issued
and the second recipe will overwrite the first. *Note Multiple
Rules for One Target: Multiple Rules.
`Circular XXX <- YYY dependency dropped.'
This means that `make' detected a loop in the dependency graph:
after tracing the prerequisite YYY of target XXX, and its
prerequisites, etc., one of them depended on XXX again.
`Recursive variable `XXX' references itself (eventually). Stop.'
This means you've defined a normal (recursive) `make' variable XXX
that, when it's expanded, will refer to itself (XXX). This is not
allowed; either use simply-expanded variables (`:=' or `::=') or
use the append operator (`+='). *Note How to Use Variables: Using
Variables.
`Unterminated variable reference. Stop.'
This means you forgot to provide the proper closing parenthesis or
brace in your variable or function reference.
`insufficient arguments to function `XXX'. Stop.'
This means you haven't provided the requisite number of arguments
for this function. See the documentation of the function for a
description of its arguments. *Note Functions for Transforming
Text: Functions.
`missing target pattern. Stop.'
`multiple target patterns. Stop.'
`target pattern contains no `%'. Stop.'
`mixed implicit and static pattern rules. Stop.'
These errors are generated for malformed static pattern rules
(*note Syntax of Static Pattern Rules: Static Usage.). The first
means the target-pattern part of the rule is empty; the second
means there are multiple pattern characters (`%') in the
target-pattern part; the third means there are no pattern
characters in the target-pattern part; and the fourth means that
all three parts of the static pattern rule contain pattern
characters (`%')-the first part should not contain pattern
characters.
If you see these errors and you aren't trying to create a static
pattern rule, check the value of any variables in your target and
prerequisite lists to be sure they do not contain colons.
`warning: -jN forced in submake: disabling jobserver mode.'
This warning and the next are generated if `make' detects error
conditions related to parallel processing on systems where
sub-`make's can communicate (*note Communicating Options to a
Sub-`make': Options/Recursion.). This warning is generated if a
recursive invocation of a `make' process is forced to have `-jN'
in its argument list (where N is greater than one). This could
happen, for example, if you set the `MAKE' environment variable to
`make -j2'. In this case, the sub-`make' doesn't communicate with
other `make' processes and will simply pretend it has two jobs of
its own.
`warning: jobserver unavailable: using -j1. Add `+' to parent make rule.'
In order for `make' processes to communicate, the parent will pass
information to the child. Since this could result in problems if
the child process isn't actually a `make', the parent will only do
this if it thinks the child is a `make'. The parent uses the
normal algorithms to determine this (*note How the `MAKE' Variable
Works: MAKE Variable.). If the makefile is constructed such that
the parent doesn't know the child is a `make' process, then the
child will receive only part of the information necessary. In
this case, the child will generate this warning message and
proceed with its build in a sequential manner.
`warning: ignoring prerequisites on suffix rule definition'
According to POSIX, a suffix rule cannot contain prerequisites.
If a rule that could be a suffix rule has prerequisites it is
interpreted as a simple explicit rule, with an odd target name.
This requirement is obeyed when POSIX-conforming mode is enabled
(the `.POSIX' target is defined). In versions of GNU `make' prior
to 4.3, no warning was emitted and a suffix rule was created,
however all prerequisites were ignored and were not part of the
suffix rule. Starting with GNU `make' 4.3 the behavior is the
same, and in addition this warning is generated. In a future
version the POSIX-conforming behavior will be the only behavior:
no rule with a prerequisite can be suffix rule and this warning
will be removed.

File: make.info, Node: Complex Makefile, Next: GNU Free Documentation License, Prev: Error Messages, Up: Top
Appendix C Complex Makefile Example
***********************************
Here is the makefile for the GNU `tar' program. This is a moderately
complex makefile. The first line uses a `#!' setting to allow the
makefile to be executed directly.
Because it is the first target, the default goal is `all'. An
interesting feature of this makefile is that `testpad.h' is a source
file automatically created by the `testpad' program, itself compiled
from `testpad.c'.
If you type `make' or `make all', then `make' creates the `tar'
executable, the `rmt' daemon that provides remote tape access, and the
`tar.info' Info file.
If you type `make install', then `make' not only creates `tar',
`rmt', and `tar.info', but also installs them.
If you type `make clean', then `make' removes the `.o' files, and
the `tar', `rmt', `testpad', `testpad.h', and `core' files.
If you type `make distclean', then `make' not only removes the same
files as does `make clean' but also the `TAGS', `Makefile', and
`config.status' files. (Although it is not evident, this makefile (and
`config.status') is generated by the user with the `configure' program,
which is provided in the `tar' distribution, but is not shown here.)
If you type `make realclean', then `make' removes the same files as
does `make distclean' and also removes the Info files generated from
`tar.texinfo'.
In addition, there are targets `shar' and `dist' that create
distribution kits.
#!/usr/bin/make -f
# Generated automatically from Makefile.in by configure.
# Un*x Makefile for GNU tar program.
# Copyright (C) 1991 Free Software Foundation, Inc.
# This program is free software; you can redistribute
# it and/or modify it under the terms of the GNU
# General Public License ...
...
...
SHELL = /bin/sh
#### Start of system configuration section. ####
srcdir = .
# If you use gcc, you should either run the
# fixincludes script that comes with it or else use
# gcc with the -traditional option. Otherwise ioctl
# calls will be compiled incorrectly on some systems.
CC = gcc -O
YACC = bison -y
INSTALL = /usr/local/bin/install -c
INSTALLDATA = /usr/local/bin/install -c -m 644
# Things you might add to DEFS:
# -DSTDC_HEADERS If you have ANSI C headers and
# libraries.
# -DPOSIX If you have POSIX.1 headers and
# libraries.
# -DBSD42 If you have sys/dir.h (unless
# you use -DPOSIX), sys/file.h,
# and st_blocks in `struct stat'.
# -DUSG If you have System V/ANSI C
# string and memory functions
# and headers, sys/sysmacros.h,
# fcntl.h, getcwd, no valloc,
# and ndir.h (unless
# you use -DDIRENT).
# -DNO_MEMORY_H If USG or STDC_HEADERS but do not
# include memory.h.
# -DDIRENT If USG and you have dirent.h
# instead of ndir.h.
# -DSIGTYPE=int If your signal handlers
# return int, not void.
# -DNO_MTIO If you lack sys/mtio.h
# (magtape ioctls).
# -DNO_REMOTE If you do not have a remote shell
# or rexec.
# -DUSE_REXEC To use rexec for remote tape
# operations instead of
# forking rsh or remsh.
# -DVPRINTF_MISSING If you lack vprintf function
# (but have _doprnt).
# -DDOPRNT_MISSING If you lack _doprnt function.
# Also need to define
# -DVPRINTF_MISSING.
# -DFTIME_MISSING If you lack ftime system call.
# -DSTRSTR_MISSING If you lack strstr function.
# -DVALLOC_MISSING If you lack valloc function.
# -DMKDIR_MISSING If you lack mkdir and
# rmdir system calls.
# -DRENAME_MISSING If you lack rename system call.
# -DFTRUNCATE_MISSING If you lack ftruncate
# system call.
# -DV7 On Version 7 Unix (not
# tested in a long time).
# -DEMUL_OPEN3 If you lack a 3-argument version
# of open, and want to emulate it
# with system calls you do have.
# -DNO_OPEN3 If you lack the 3-argument open
# and want to disable the tar -k
# option instead of emulating open.
# -DXENIX If you have sys/inode.h
# and need it 94 to be included.
DEFS = -DSIGTYPE=int -DDIRENT -DSTRSTR_MISSING \
-DVPRINTF_MISSING -DBSD42
# Set this to rtapelib.o unless you defined NO_REMOTE,
# in which case make it empty.
RTAPELIB = rtapelib.o
LIBS =
DEF_AR_FILE = /dev/rmt8
DEFBLOCKING = 20
CDEBUG = -g
CFLAGS = $(CDEBUG) -I. -I$(srcdir) $(DEFS) \
-DDEF_AR_FILE=\"$(DEF_AR_FILE)\" \
-DDEFBLOCKING=$(DEFBLOCKING)
LDFLAGS = -g
prefix = /usr/local
# Prefix for each installed program,
# normally empty or `g'.
binprefix =
# The directory to install tar in.
bindir = $(prefix)/bin
# The directory to install the info files in.
infodir = $(prefix)/info
#### End of system configuration section. ####
SRCS_C = tar.c create.c extract.c buffer.c \
getoldopt.c update.c gnu.c mangle.c \
version.c list.c names.c diffarch.c \
port.c wildmat.c getopt.c getopt1.c \
regex.c
SRCS_Y = getdate.y
SRCS = $(SRCS_C) $(SRCS_Y)
OBJS = $(SRCS_C:.c=.o) $(SRCS_Y:.y=.o) $(RTAPELIB)
AUX = README COPYING ChangeLog Makefile.in \
makefile.pc configure configure.in \
tar.texinfo tar.info* texinfo.tex \
tar.h port.h open3.h getopt.h regex.h \
rmt.h rmt.c rtapelib.c alloca.c \
msd_dir.h msd_dir.c tcexparg.c \
level-0 level-1 backup-specs testpad.c
.PHONY: all
all: tar rmt tar.info
tar: $(OBJS)
$(CC) $(LDFLAGS) -o $@ $(OBJS) $(LIBS)
rmt: rmt.c
$(CC) $(CFLAGS) $(LDFLAGS) -o $@ rmt.c
tar.info: tar.texinfo
makeinfo tar.texinfo
.PHONY: install
install: all
$(INSTALL) tar $(bindir)/$(binprefix)tar
-test ! -f rmt || $(INSTALL) rmt /etc/rmt
$(INSTALLDATA) $(srcdir)/tar.info* $(infodir)
$(OBJS): tar.h port.h testpad.h
regex.o buffer.o tar.o: regex.h
# getdate.y has 8 shift/reduce conflicts.
testpad.h: testpad
./testpad
testpad: testpad.o
$(CC) -o $@ testpad.o
TAGS: $(SRCS)
etags $(SRCS)
.PHONY: clean
clean:
rm -f *.o tar rmt testpad testpad.h core
.PHONY: distclean
distclean: clean
rm -f TAGS Makefile config.status
.PHONY: realclean
realclean: distclean
rm -f tar.info*
.PHONY: shar
shar: $(SRCS) $(AUX)
shar $(SRCS) $(AUX) | compress \
> tar-`sed -e '/version_string/!d' \
-e 's/[^0-9.]*\([0-9.]*\).*/\1/' \
-e q
version.c`.shar.Z
.PHONY: dist
dist: $(SRCS) $(AUX)
echo tar-`sed \
-e '/version_string/!d' \
-e 's/[^0-9.]*\([0-9.]*\).*/\1/' \
-e q
version.c` > .fname
-rm -rf `cat .fname`
mkdir `cat .fname`
ln $(SRCS) $(AUX) `cat .fname`
tar chZf `cat .fname`.tar.Z `cat .fname`
-rm -rf `cat .fname` .fname
tar.zoo: $(SRCS) $(AUX)
-rm -rf tmp.dir
-mkdir tmp.dir
-rm tar.zoo
for X in $(SRCS) $(AUX) ; do \
echo $$X ; \
sed 's/$$/^M/' $$X \
> tmp.dir/$$X ; done
cd tmp.dir ; zoo aM ../tar.zoo *
-rm -rf tmp.dir

File: make.info, Node: GNU Free Documentation License, Next: Concept Index, Prev: Complex Makefile, Up: Top
Appendix D GNU Free Documentation License
*****************************************
Version 1.3, 3 November 2008
Copyright (C) 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc.
`https://fsf.org/'
Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
0. PREAMBLE
The purpose of this License is to make a manual, textbook, or other
functional and useful document "free" in the sense of freedom: to
assure everyone the effective freedom to copy and redistribute it,
with or without modifying it, either commercially or
noncommercially. Secondarily, this License preserves for the
author and publisher a way to get credit for their work, while not
being considered responsible for modifications made by others.
This License is a kind of "copyleft", which means that derivative
works of the document must themselves be free in the same sense.
It complements the GNU General Public License, which is a copyleft
license designed for free software.
We have designed this License in order to use it for manuals for
free software, because free software needs free documentation: a
free program should come with manuals providing the same freedoms
that the software does. But this License is not limited to
software manuals; it can be used for any textual work, regardless
of subject matter or whether it is published as a printed book.
We recommend this License principally for works whose purpose is
instruction or reference.
1. APPLICABILITY AND DEFINITIONS
This License applies to any manual or other work, in any medium,
that contains a notice placed by the copyright holder saying it
can be distributed under the terms of this License. Such a notice
grants a world-wide, royalty-free license, unlimited in duration,
to use that work under the conditions stated herein. The
"Document", below, refers to any such manual or work. Any member
of the public is a licensee, and is addressed as "you". You
accept the license if you copy, modify or distribute the work in a
way requiring permission under copyright law.
A "Modified Version" of the Document means any work containing the
Document or a portion of it, either copied verbatim, or with
modifications and/or translated into another language.
A "Secondary Section" is a named appendix or a front-matter section
of the Document that deals exclusively with the relationship of the
publishers or authors of the Document to the Document's overall
subject (or to related matters) and contains nothing that could
fall directly within that overall subject. (Thus, if the Document
is in part a textbook of mathematics, a Secondary Section may not
explain any mathematics.) The relationship could be a matter of
historical connection with the subject or with related matters, or
of legal, commercial, philosophical, ethical or political position
regarding them.
The "Invariant Sections" are certain Secondary Sections whose
titles are designated, as being those of Invariant Sections, in
the notice that says that the Document is released under this
License. If a section does not fit the above definition of
Secondary then it is not allowed to be designated as Invariant.
The Document may contain zero Invariant Sections. If the Document
does not identify any Invariant Sections then there are none.
The "Cover Texts" are certain short passages of text that are
listed, as Front-Cover Texts or Back-Cover Texts, in the notice
that says that the Document is released under this License. A
Front-Cover Text may be at most 5 words, and a Back-Cover Text may
be at most 25 words.
A "Transparent" copy of the Document means a machine-readable copy,
represented in a format whose specification is available to the
general public, that is suitable for revising the document
straightforwardly with generic text editors or (for images
composed of pixels) generic paint programs or (for drawings) some
widely available drawing editor, and that is suitable for input to
text formatters or for automatic translation to a variety of
formats suitable for input to text formatters. A copy made in an
otherwise Transparent file format whose markup, or absence of
markup, has been arranged to thwart or discourage subsequent
modification by readers is not Transparent. An image format is
not Transparent if used for any substantial amount of text. A
copy that is not "Transparent" is called "Opaque".
Examples of suitable formats for Transparent copies include plain
ASCII without markup, Texinfo input format, LaTeX input format,
SGML or XML using a publicly available DTD, and
standard-conforming simple HTML, PostScript or PDF designed for
human modification. Examples of transparent image formats include
PNG, XCF and JPG. Opaque formats include proprietary formats that
can be read and edited only by proprietary word processors, SGML or
XML for which the DTD and/or processing tools are not generally
available, and the machine-generated HTML, PostScript or PDF
produced by some word processors for output purposes only.
The "Title Page" means, for a printed book, the title page itself,
plus such following pages as are needed to hold, legibly, the
material this License requires to appear in the title page. For
works in formats which do not have any title page as such, "Title
Page" means the text near the most prominent appearance of the
work's title, preceding the beginning of the body of the text.
The "publisher" means any person or entity that distributes copies
of the Document to the public.
A section "Entitled XYZ" means a named subunit of the Document
whose title either is precisely XYZ or contains XYZ in parentheses
following text that translates XYZ in another language. (Here XYZ
stands for a specific section name mentioned below, such as
"Acknowledgements", "Dedications", "Endorsements", or "History".)
To "Preserve the Title" of such a section when you modify the
Document means that it remains a section "Entitled XYZ" according
to this definition.
The Document may include Warranty Disclaimers next to the notice
which states that this License applies to the Document. These
Warranty Disclaimers are considered to be included by reference in
this License, but only as regards disclaiming warranties: any other
implication that these Warranty Disclaimers may have is void and
has no effect on the meaning of this License.
2. VERBATIM COPYING
You may copy and distribute the Document in any medium, either
commercially or noncommercially, provided that this License, the
copyright notices, and the license notice saying this License
applies to the Document are reproduced in all copies, and that you
add no other conditions whatsoever to those of this License. You
may not use technical measures to obstruct or control the reading
or further copying of the copies you make or distribute. However,
you may accept compensation in exchange for copies. If you
distribute a large enough number of copies you must also follow
the conditions in section 3.
You may also lend copies, under the same conditions stated above,
and you may publicly display copies.
3. COPYING IN QUANTITY
If you publish printed copies (or copies in media that commonly
have printed covers) of the Document, numbering more than 100, and
the Document's license notice requires Cover Texts, you must
enclose the copies in covers that carry, clearly and legibly, all
these Cover Texts: Front-Cover Texts on the front cover, and
Back-Cover Texts on the back cover. Both covers must also clearly
and legibly identify you as the publisher of these copies. The
front cover must present the full title with all words of the
title equally prominent and visible. You may add other material
on the covers in addition. Copying with changes limited to the
covers, as long as they preserve the title of the Document and
satisfy these conditions, can be treated as verbatim copying in
other respects.
If the required texts for either cover are too voluminous to fit
legibly, you should put the first ones listed (as many as fit
reasonably) on the actual cover, and continue the rest onto
adjacent pages.
If you publish or distribute Opaque copies of the Document
numbering more than 100, you must either include a
machine-readable Transparent copy along with each Opaque copy, or
state in or with each Opaque copy a computer-network location from
which the general network-using public has access to download
using public-standard network protocols a complete Transparent
copy of the Document, free of added material. If you use the
latter option, you must take reasonably prudent steps, when you
begin distribution of Opaque copies in quantity, to ensure that
this Transparent copy will remain thus accessible at the stated
location until at least one year after the last time you
distribute an Opaque copy (directly or through your agents or
retailers) of that edition to the public.
It is requested, but not required, that you contact the authors of
the Document well before redistributing any large number of
copies, to give them a chance to provide you with an updated
version of the Document.
4. MODIFICATIONS
You may copy and distribute a Modified Version of the Document
under the conditions of sections 2 and 3 above, provided that you
release the Modified Version under precisely this License, with
the Modified Version filling the role of the Document, thus
licensing distribution and modification of the Modified Version to
whoever possesses a copy of it. In addition, you must do these
things in the Modified Version:
A. Use in the Title Page (and on the covers, if any) a title
distinct from that of the Document, and from those of
previous versions (which should, if there were any, be listed
in the History section of the Document). You may use the
same title as a previous version if the original publisher of
that version gives permission.
B. List on the Title Page, as authors, one or more persons or
entities responsible for authorship of the modifications in
the Modified Version, together with at least five of the
principal authors of the Document (all of its principal
authors, if it has fewer than five), unless they release you
from this requirement.
C. State on the Title page the name of the publisher of the
Modified Version, as the publisher.
D. Preserve all the copyright notices of the Document.
E. Add an appropriate copyright notice for your modifications
adjacent to the other copyright notices.
F. Include, immediately after the copyright notices, a license
notice giving the public permission to use the Modified
Version under the terms of this License, in the form shown in
the Addendum below.
G. Preserve in that license notice the full lists of Invariant
Sections and required Cover Texts given in the Document's
license notice.
H. Include an unaltered copy of this License.
I. Preserve the section Entitled "History", Preserve its Title,
and add to it an item stating at least the title, year, new
authors, and publisher of the Modified Version as given on
the Title Page. If there is no section Entitled "History" in
the Document, create one stating the title, year, authors,
and publisher of the Document as given on its Title Page,
then add an item describing the Modified Version as stated in
the previous sentence.
J. Preserve the network location, if any, given in the Document
for public access to a Transparent copy of the Document, and
likewise the network locations given in the Document for
previous versions it was based on. These may be placed in
the "History" section. You may omit a network location for a
work that was published at least four years before the
Document itself, or if the original publisher of the version
it refers to gives permission.
K. For any section Entitled "Acknowledgements" or "Dedications",
Preserve the Title of the section, and preserve in the
section all the substance and tone of each of the contributor
acknowledgements and/or dedications given therein.
L. Preserve all the Invariant Sections of the Document,
unaltered in their text and in their titles. Section numbers
or the equivalent are not considered part of the section
titles.
M. Delete any section Entitled "Endorsements". Such a section
may not be included in the Modified Version.
N. Do not retitle any existing section to be Entitled
"Endorsements" or to conflict in title with any Invariant
Section.
O. Preserve any Warranty Disclaimers.
If the Modified Version includes new front-matter sections or
appendices that qualify as Secondary Sections and contain no
material copied from the Document, you may at your option
designate some or all of these sections as invariant. To do this,
add their titles to the list of Invariant Sections in the Modified
Version's license notice. These titles must be distinct from any
other section titles.
You may add a section Entitled "Endorsements", provided it contains
nothing but endorsements of your Modified Version by various
parties--for example, statements of peer review or that the text
has been approved by an organization as the authoritative
definition of a standard.
You may add a passage of up to five words as a Front-Cover Text,
and a passage of up to 25 words as a Back-Cover Text, to the end
of the list of Cover Texts in the Modified Version. Only one
passage of Front-Cover Text and one of Back-Cover Text may be
added by (or through arrangements made by) any one entity. If the
Document already includes a cover text for the same cover,
previously added by you or by arrangement made by the same entity
you are acting on behalf of, you may not add another; but you may
replace the old one, on explicit permission from the previous
publisher that added the old one.
The author(s) and publisher(s) of the Document do not by this
License give permission to use their names for publicity for or to
assert or imply endorsement of any Modified Version.
5. COMBINING DOCUMENTS
You may combine the Document with other documents released under
this License, under the terms defined in section 4 above for
modified versions, provided that you include in the combination
all of the Invariant Sections of all of the original documents,
unmodified, and list them all as Invariant Sections of your
combined work in its license notice, and that you preserve all
their Warranty Disclaimers.
The combined work need only contain one copy of this License, and
multiple identical Invariant Sections may be replaced with a single
copy. If there are multiple Invariant Sections with the same name
but different contents, make the title of each such section unique
by adding at the end of it, in parentheses, the name of the
original author or publisher of that section if known, or else a
unique number. Make the same adjustment to the section titles in
the list of Invariant Sections in the license notice of the
combined work.
In the combination, you must combine any sections Entitled
"History" in the various original documents, forming one section
Entitled "History"; likewise combine any sections Entitled
"Acknowledgements", and any sections Entitled "Dedications". You
must delete all sections Entitled "Endorsements."
6. COLLECTIONS OF DOCUMENTS
You may make a collection consisting of the Document and other
documents released under this License, and replace the individual
copies of this License in the various documents with a single copy
that is included in the collection, provided that you follow the
rules of this License for verbatim copying of each of the
documents in all other respects.
You may extract a single document from such a collection, and
distribute it individually under this License, provided you insert
a copy of this License into the extracted document, and follow
this License in all other respects regarding verbatim copying of
that document.
7. AGGREGATION WITH INDEPENDENT WORKS
A compilation of the Document or its derivatives with other
separate and independent documents or works, in or on a volume of
a storage or distribution medium, is called an "aggregate" if the
copyright resulting from the compilation is not used to limit the
legal rights of the compilation's users beyond what the individual
works permit. When the Document is included in an aggregate, this
License does not apply to the other works in the aggregate which
are not themselves derivative works of the Document.
If the Cover Text requirement of section 3 is applicable to these
copies of the Document, then if the Document is less than one half
of the entire aggregate, the Document's Cover Texts may be placed
on covers that bracket the Document within the aggregate, or the
electronic equivalent of covers if the Document is in electronic
form. Otherwise they must appear on printed covers that bracket
the whole aggregate.
8. TRANSLATION
Translation is considered a kind of modification, so you may
distribute translations of the Document under the terms of section
4. Replacing Invariant Sections with translations requires special
permission from their copyright holders, but you may include
translations of some or all Invariant Sections in addition to the
original versions of these Invariant Sections. You may include a
translation of this License, and all the license notices in the
Document, and any Warranty Disclaimers, provided that you also
include the original English version of this License and the
original versions of those notices and disclaimers. In case of a
disagreement between the translation and the original version of
this License or a notice or disclaimer, the original version will
prevail.
If a section in the Document is Entitled "Acknowledgements",
"Dedications", or "History", the requirement (section 4) to
Preserve its Title (section 1) will typically require changing the
actual title.
9. TERMINATION
You may not copy, modify, sublicense, or distribute the Document
except as expressly provided under this License. Any attempt
otherwise to copy, modify, sublicense, or distribute it is void,
and will automatically terminate your rights under this License.
However, if you cease all violation of this License, then your
license from a particular copyright holder is reinstated (a)
provisionally, unless and until the copyright holder explicitly
and finally terminates your license, and (b) permanently, if the
copyright holder fails to notify you of the violation by some
reasonable means prior to 60 days after the cessation.
Moreover, your license from a particular copyright holder is
reinstated permanently if the copyright holder notifies you of the
violation by some reasonable means, this is the first time you have
received notice of violation of this License (for any work) from
that copyright holder, and you cure the violation prior to 30 days
after your receipt of the notice.
Termination of your rights under this section does not terminate
the licenses of parties who have received copies or rights from
you under this License. If your rights have been terminated and
not permanently reinstated, receipt of a copy of some or all of
the same material does not give you any rights to use it.
10. FUTURE REVISIONS OF THIS LICENSE
The Free Software Foundation may publish new, revised versions of
the GNU Free Documentation License from time to time. Such new
versions will be similar in spirit to the present version, but may
differ in detail to address new problems or concerns. See
`https://www.gnu.org/copyleft/'.
Each version of the License is given a distinguishing version
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version of this License "or any later version" applies to it, you
have the option of following the terms and conditions either of
that specified version or of any later version that has been
published (not as a draft) by the Free Software Foundation. If
the Document does not specify a version number of this License,
you may choose any version ever published (not as a draft) by the
Free Software Foundation. If the Document specifies that a proxy
can decide which future versions of this License can be used, that
proxy's public statement of acceptance of a version permanently
authorizes you to choose that version for the Document.
11. RELICENSING
"Massive Multiauthor Collaboration Site" (or "MMC Site") means any
World Wide Web server that publishes copyrightable works and also
provides prominent facilities for anybody to edit those works. A
public wiki that anybody can edit is an example of such a server.
A "Massive Multiauthor Collaboration" (or "MMC") contained in the
site means any set of copyrightable works thus published on the MMC
site.
"CC-BY-SA" means the Creative Commons Attribution-Share Alike 3.0
license published by Creative Commons Corporation, a not-for-profit
corporation with a principal place of business in San Francisco,
California, as well as future copyleft versions of that license
published by that same organization.
"Incorporate" means to publish or republish a Document, in whole or
in part, as part of another Document.
An MMC is "eligible for relicensing" if it is licensed under this
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to November 1, 2008.
The operator of an MMC Site may republish an MMC contained in the
site under CC-BY-SA on the same site at any time before August 1,
2009, provided the MMC is eligible for relicensing.
ADDENDUM: How to use this License for your documents
====================================================
To use this License in a document you have written, include a copy of
the License in the document and put the following copyright and license
notices just after the title page:
Copyright (C) YEAR YOUR NAME.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3
or any later version published by the Free Software Foundation;
with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
Texts. A copy of the license is included in the section entitled ``GNU
Free Documentation License''.
If you have Invariant Sections, Front-Cover Texts and Back-Cover
Texts, replace the "with...Texts." line with this:
with the Invariant Sections being LIST THEIR TITLES, with
the Front-Cover Texts being LIST, and with the Back-Cover Texts
being LIST.
If you have Invariant Sections without Cover Texts, or some other
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If your document contains nontrivial examples of program code, we
recommend releasing these examples in parallel under your choice of
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permit their use in free software.

File: make.info, Node: Concept Index, Next: Name Index, Prev: GNU Free Documentation License, Up: Top
Index of Concepts
*****************
�[index�]
* Menu:
* !=: Setting. (line 6)
* !=, expansion: Reading Makefiles. (line 34)
* # (comments), in makefile: Makefile Contents. (line 42)
* # (comments), in recipes: Recipe Syntax. (line 29)
* #include: Automatic Prerequisites.
(line 16)
* $, in function call: Syntax of Functions. (line 6)
* $, in rules: Rule Syntax. (line 34)
* $, in variable name: Computed Names. (line 6)
* $, in variable reference: Reference. (line 6)
* %, in pattern rules: Pattern Intro. (line 9)
* %, quoting in patsubst: Text Functions. (line 26)
* %, quoting in static pattern: Static Usage. (line 37)
* %, quoting in vpath: Selective Search. (line 38)
* %, quoting with \ (backslash) <1>: Selective Search. (line 38)
* %, quoting with \ (backslash) <2>: Text Functions. (line 26)
* %, quoting with \ (backslash): Static Usage. (line 37)
* * (wildcard character): Wildcards. (line 6)
* +, and define: Canned Recipes. (line 49)
* +, and recipe execution: Instead of Execution.
(line 63)
* +, and recipes: MAKE Variable. (line 18)
* +=: Appending. (line 6)
* +=, expansion: Reading Makefiles. (line 34)
* ,v (RCS file extension): Catalogue of Rules. (line 164)
* - (in recipes): Errors. (line 19)
* -, and define: Canned Recipes. (line 49)
* --always-make: Options Summary. (line 15)
* --assume-new <1>: Instead of Execution.
(line 38)
* --assume-new: Options Summary. (line 278)
* --assume-new, and recursion: Options/Recursion. (line 22)
* --assume-old <1>: Avoiding Compilation.
(line 6)
* --assume-old: Options Summary. (line 161)
* --assume-old, and recursion: Options/Recursion. (line 22)
* --check-symlink-times: Options Summary. (line 143)
* --debug: Options Summary. (line 42)
* --directory <1>: Options Summary. (line 26)
* --directory: Recursion. (line 20)
* --directory, and --print-directory: -w Option. (line 20)
* --directory, and recursion: Options/Recursion. (line 22)
* --dry-run <1>: Instead of Execution.
(line 14)
* --dry-run <2>: Echoing. (line 18)
* --dry-run: Options Summary. (line 153)
* --environment-overrides: Options Summary. (line 83)
* --eval: Options Summary. (line 90)
* --file <1>: Options Summary. (line 97)
* --file <2>: Makefile Names. (line 23)
* --file: Makefile Arguments. (line 6)
* --file, and recursion: Options/Recursion. (line 22)
* --help: Options Summary. (line 103)
* --ignore-errors <1>: Options Summary. (line 107)
* --ignore-errors: Errors. (line 30)
* --include-dir <1>: Include. (line 53)
* --include-dir: Options Summary. (line 112)
* --jobs <1>: Options Summary. (line 119)
* --jobs: Parallel. (line 6)
* --jobs, and recursion: Options/Recursion. (line 25)
* --just-print <1>: Options Summary. (line 152)
* --just-print <2>: Instead of Execution.
(line 14)
* --just-print: Echoing. (line 18)
* --keep-going <1>: Errors. (line 46)
* --keep-going <2>: Options Summary. (line 128)
* --keep-going: Testing. (line 16)
* --load-average <1>: Options Summary. (line 135)
* --load-average: Parallel. (line 35)
* --makefile <1>: Makefile Arguments. (line 6)
* --makefile <2>: Options Summary. (line 98)
* --makefile: Makefile Names. (line 23)
* --max-load <1>: Parallel. (line 35)
* --max-load: Options Summary. (line 136)
* --new-file <1>: Instead of Execution.
(line 38)
* --new-file: Options Summary. (line 277)
* --new-file, and recursion: Options/Recursion. (line 22)
* --no-builtin-rules: Options Summary. (line 205)
* --no-builtin-variables: Options Summary. (line 218)
* --no-keep-going: Options Summary. (line 233)
* --no-print-directory <1>: Options Summary. (line 269)
* --no-print-directory: -w Option. (line 20)
* --old-file <1>: Avoiding Compilation.
(line 6)
* --old-file: Options Summary. (line 160)
* --old-file, and recursion: Options/Recursion. (line 22)
* --output-sync <1>: Options Summary. (line 169)
* --output-sync: Parallel Output. (line 11)
* --print-data-base: Options Summary. (line 185)
* --print-directory: Options Summary. (line 261)
* --print-directory, and --directory: -w Option. (line 20)
* --print-directory, and recursion: -w Option. (line 20)
* --print-directory, disabling: -w Option. (line 20)
* --question <1>: Instead of Execution.
(line 30)
* --question: Options Summary. (line 197)
* --quiet <1>: Echoing. (line 24)
* --quiet: Options Summary. (line 228)
* --recon <1>: Options Summary. (line 154)
* --recon <2>: Echoing. (line 18)
* --recon: Instead of Execution.
(line 14)
* --silent <1>: Options Summary. (line 227)
* --silent: Echoing. (line 24)
* --stop: Options Summary. (line 234)
* --touch <1>: Options Summary. (line 242)
* --touch: Instead of Execution.
(line 23)
* --touch, and recursion: MAKE Variable. (line 34)
* --trace: Options Summary. (line 248)
* --version: Options Summary. (line 256)
* --warn-undefined-variables: Options Summary. (line 287)
* --what-if <1>: Options Summary. (line 276)
* --what-if: Instead of Execution.
(line 38)
* -B: Options Summary. (line 14)
* -b: Options Summary. (line 9)
* -C <1>: Recursion. (line 20)
* -C: Options Summary. (line 25)
* -C, and -w: -w Option. (line 20)
* -C, and recursion: Options/Recursion. (line 22)
* -d: Options Summary. (line 33)
* -E: Options Summary. (line 88)
* -e: Options Summary. (line 82)
* -e (shell flag): Automatic Prerequisites.
(line 66)
* -f <1>: Options Summary. (line 96)
* -f <2>: Makefile Names. (line 23)
* -f: Makefile Arguments. (line 6)
* -f, and recursion: Options/Recursion. (line 22)
* -h: Options Summary. (line 102)
* -I <1>: Include. (line 53)
* -I: Options Summary. (line 111)
* -i <1>: Errors. (line 30)
* -i: Options Summary. (line 106)
* -j <1>: Parallel. (line 6)
* -j: Options Summary. (line 118)
* -j, and archive update: Archive Pitfalls. (line 6)
* -j, and recursion: Options/Recursion. (line 25)
* -k <1>: Errors. (line 46)
* -k <2>: Testing. (line 16)
* -k: Options Summary. (line 127)
* -L: Options Summary. (line 142)
* -l: Options Summary. (line 134)
* -l (library search): Libraries/Search. (line 6)
* -l (load average): Parallel. (line 35)
* -m: Options Summary. (line 10)
* -M (to compiler): Automatic Prerequisites.
(line 18)
* -MM (to GNU compiler): Automatic Prerequisites.
(line 68)
* -n <1>: Instead of Execution.
(line 14)
* -n <2>: Options Summary. (line 151)
* -n: Echoing. (line 18)
* -O: Options Summary. (line 168)
* -o <1>: Avoiding Compilation.
(line 6)
* -o: Options Summary. (line 159)
* -O: Parallel Output. (line 11)
* -o, and recursion: Options/Recursion. (line 22)
* -p: Options Summary. (line 184)
* -q <1>: Instead of Execution.
(line 30)
* -q: Options Summary. (line 196)
* -r: Options Summary. (line 204)
* -R: Options Summary. (line 217)
* -S: Options Summary. (line 232)
* -s <1>: Echoing. (line 24)
* -s: Options Summary. (line 226)
* -t <1>: Options Summary. (line 241)
* -t: Instead of Execution.
(line 23)
* -t, and recursion: MAKE Variable. (line 34)
* -v: Options Summary. (line 255)
* -w: Options Summary. (line 260)
* -W <1>: Options Summary. (line 275)
* -W: Instead of Execution.
(line 38)
* -w, and -C: -w Option. (line 20)
* -w, and recursion: -w Option. (line 20)
* -W, and recursion: Options/Recursion. (line 22)
* -w, disabling: -w Option. (line 20)
* .a (archives): Archive Suffix Rules.
(line 6)
* .c: Catalogue of Rules. (line 35)
* .C: Catalogue of Rules. (line 39)
* .cc: Catalogue of Rules. (line 39)
* .ch: Catalogue of Rules. (line 151)
* .cpp: Catalogue of Rules. (line 39)
* .d: Automatic Prerequisites.
(line 81)
* .def: Catalogue of Rules. (line 74)
* .dvi: Catalogue of Rules. (line 151)
* .f: Catalogue of Rules. (line 49)
* .F: Catalogue of Rules. (line 49)
* .info: Catalogue of Rules. (line 158)
* .l: Catalogue of Rules. (line 124)
* .LIBPATTERNS, and link libraries: Libraries/Search. (line 6)
* .ln: Catalogue of Rules. (line 146)
* .mod: Catalogue of Rules. (line 74)
* .o: Catalogue of Rules. (line 86)
* .ONESHELL, use of: One Shell. (line 6)
* .p: Catalogue of Rules. (line 45)
* .PRECIOUS intermediate files: Chained Rules. (line 56)
* .r: Catalogue of Rules. (line 49)
* .S: Catalogue of Rules. (line 82)
* .s: Catalogue of Rules. (line 79)
* .sh: Catalogue of Rules. (line 180)
* .SHELLFLAGS, value of: Choosing the Shell. (line 6)
* .sym: Catalogue of Rules. (line 74)
* .tex: Catalogue of Rules. (line 151)
* .texi: Catalogue of Rules. (line 158)
* .texinfo: Catalogue of Rules. (line 158)
* .txinfo: Catalogue of Rules. (line 158)
* .w: Catalogue of Rules. (line 151)
* .web: Catalogue of Rules. (line 151)
* .y: Catalogue of Rules. (line 120)
* :: rules (double-colon): Double-Colon. (line 6)
* ::= <1>: Setting. (line 6)
* ::=: Flavors. (line 56)
* := <1>: Flavors. (line 56)
* :=: Setting. (line 6)
* = <1>: Setting. (line 6)
* =: Flavors. (line 10)
* =, expansion: Reading Makefiles. (line 34)
* ? (wildcard character): Wildcards. (line 6)
* ?= <1>: Setting. (line 6)
* ?=: Flavors. (line 133)
* ?=, expansion: Reading Makefiles. (line 34)
* @ (in recipes): Echoing. (line 6)
* @, and define: Canned Recipes. (line 49)
* [...] (wildcard characters): Wildcards. (line 6)
* \ (backslash), for continuation lines: Simple Makefile. (line 41)
* \ (backslash), in recipes: Splitting Recipe Lines.
(line 6)
* \ (backslash), to quote % <1>: Selective Search. (line 38)
* \ (backslash), to quote % <2>: Static Usage. (line 37)
* \ (backslash), to quote %: Text Functions. (line 26)
* __.SYMDEF: Archive Symbols. (line 6)
* abspath: File Name Functions. (line 121)
* algorithm for directory search: Search Algorithm. (line 6)
* all (standard target): Goals. (line 72)
* appending to variables: Appending. (line 6)
* ar: Implicit Variables. (line 40)
* archive: Archives. (line 6)
* archive member targets: Archive Members. (line 6)
* archive symbol directory updating: Archive Symbols. (line 6)
* archive, and -j: Archive Pitfalls. (line 6)
* archive, and parallel execution: Archive Pitfalls. (line 6)
* archive, suffix rule for: Archive Suffix Rules.
(line 6)
* Arg list too long: Options/Recursion. (line 57)
* arguments of functions: Syntax of Functions. (line 6)
* as <1>: Catalogue of Rules. (line 79)
* as: Implicit Variables. (line 43)
* assembly, rule to compile: Catalogue of Rules. (line 79)
* automatic generation of prerequisites <1>: Automatic Prerequisites.
(line 6)
* automatic generation of prerequisites: Include. (line 51)
* automatic variables: Automatic Variables. (line 6)
* automatic variables in prerequisites: Automatic Variables. (line 17)
* backquotes: Shell Function. (line 6)
* backslash (\), for continuation lines: Simple Makefile. (line 41)
* backslash (\), in recipes: Splitting Recipe Lines.
(line 6)
* backslash (\), to quote % <1>: Selective Search. (line 38)
* backslash (\), to quote % <2>: Text Functions. (line 26)
* backslash (\), to quote %: Static Usage. (line 37)
* backslash (\), to quote newlines: Splitting Lines. (line 6)
* backslashes in pathnames and wildcard expansion: Wildcard Pitfall.
(line 31)
* basename: File Name Functions. (line 57)
* binary packages: Install Command Categories.
(line 80)
* broken pipe: Parallel Input. (line 11)
* bugs, reporting: Bugs. (line 6)
* built-in special targets: Special Targets. (line 6)
* C++, rule to compile: Catalogue of Rules. (line 39)
* C, rule to compile: Catalogue of Rules. (line 35)
* canned recipes: Canned Recipes. (line 6)
* cc <1>: Implicit Variables. (line 46)
* cc: Catalogue of Rules. (line 35)
* cd (shell command) <1>: Execution. (line 12)
* cd (shell command): MAKE Variable. (line 16)
* chains of rules: Chained Rules. (line 6)
* check (standard target): Goals. (line 114)
* clean (standard target): Goals. (line 75)
* clean target <1>: Cleanup. (line 11)
* clean target: Simple Makefile. (line 85)
* cleaning up: Cleanup. (line 6)
* clobber (standard target): Goals. (line 86)
* co <1>: Implicit Variables. (line 66)
* co: Catalogue of Rules. (line 164)
* combining rules by prerequisite: Combine By Prerequisite.
(line 6)
* command expansion: Shell Function. (line 6)
* command line variable definitions, and recursion: Options/Recursion.
(line 17)
* command line variables: Overriding. (line 6)
* commands, sequences of: Canned Recipes. (line 6)
* comments, in makefile: Makefile Contents. (line 42)
* comments, in recipes: Recipe Syntax. (line 29)
* compatibility: Features. (line 6)
* compatibility in exporting: Variables/Recursion. (line 105)
* compilation, testing: Testing. (line 6)
* computed variable name: Computed Names. (line 6)
* conditional expansion: Conditional Functions.
(line 6)
* conditional variable assignment: Flavors. (line 133)
* conditionals: Conditionals. (line 6)
* continuation lines: Simple Makefile. (line 41)
* controlling make: Make Control Functions.
(line 6)
* conventions for makefiles: Makefile Conventions.
(line 6)
* convert guile types: Guile Types. (line 6)
* ctangle <1>: Implicit Variables. (line 103)
* ctangle: Catalogue of Rules. (line 151)
* cweave <1>: Implicit Variables. (line 97)
* cweave: Catalogue of Rules. (line 151)
* data base of make rules: Options Summary. (line 185)
* deducing recipes (implicit rules): make Deduces. (line 6)
* default directories for included makefiles: Include. (line 53)
* default goal <1>: Rules. (line 11)
* default goal: How Make Works. (line 11)
* default makefile name: Makefile Names. (line 6)
* default rules, last-resort: Last Resort. (line 6)
* define, expansion: Reading Makefiles. (line 34)
* defining variables verbatim: Multi-Line. (line 6)
* deletion of target files <1>: Interrupts. (line 6)
* deletion of target files: Errors. (line 63)
* directive: Makefile Contents. (line 28)
* directories, creating installation: Directory Variables. (line 20)
* directories, printing them: -w Option. (line 6)
* directories, updating archive symbol: Archive Symbols. (line 6)
* directory part: File Name Functions. (line 17)
* directory search (VPATH): Directory Search. (line 6)
* directory search (VPATH), and implicit rules: Implicit/Search.
(line 6)
* directory search (VPATH), and link libraries: Libraries/Search.
(line 6)
* directory search (VPATH), and recipes: Recipes/Search. (line 6)
* directory search algorithm: Search Algorithm. (line 6)
* directory search, traditional (GPATH): Search Algorithm. (line 42)
* dist (standard target): Goals. (line 106)
* distclean (standard target): Goals. (line 84)
* dollar sign ($), in function call: Syntax of Functions. (line 6)
* dollar sign ($), in rules: Rule Syntax. (line 34)
* dollar sign ($), in variable name: Computed Names. (line 6)
* dollar sign ($), in variable reference: Reference. (line 6)
* DOS, choosing a shell in: Choosing the Shell. (line 38)
* double-colon rules: Double-Colon. (line 6)
* duplicate words, removing: Text Functions. (line 155)
* E2BIG: Options/Recursion. (line 57)
* echoing of recipes: Echoing. (line 6)
* editor: Introduction. (line 22)
* Emacs (M-x compile): Errors. (line 61)
* empty recipes: Empty Recipes. (line 6)
* empty targets: Empty Targets. (line 6)
* environment: Environment. (line 6)
* environment, and recursion: Variables/Recursion. (line 6)
* environment, SHELL in: Choosing the Shell. (line 12)
* error, stopping on: Make Control Functions.
(line 11)
* errors (in recipes): Errors. (line 6)
* errors with wildcards: Wildcard Pitfall. (line 6)
* evaluating makefile syntax: Eval Function. (line 6)
* example of loaded objects: Loaded Object Example.
(line 6)
* example using Guile: Guile Example. (line 6)
* execution, in parallel: Parallel. (line 6)
* execution, instead of: Instead of Execution.
(line 6)
* execution, of recipes: Execution. (line 6)
* exit status (errors): Errors. (line 6)
* exit status of make: Running. (line 18)
* expansion, secondary: Secondary Expansion. (line 6)
* explicit rule, definition of: Makefile Contents. (line 10)
* explicit rule, expansion: Reading Makefiles. (line 93)
* explicit rules, secondary expansion of: Secondary Expansion.
(line 105)
* exporting variables: Variables/Recursion. (line 6)
* extensions, Guile: Guile Integration. (line 6)
* extensions, load directive: load Directive. (line 6)
* extensions, loading: Loading Objects. (line 6)
* f77 <1>: Implicit Variables. (line 57)
* f77: Catalogue of Rules. (line 49)
* FDL, GNU Free Documentation License: GNU Free Documentation License.
(line 6)
* features of GNU make: Features. (line 6)
* features, missing: Missing. (line 6)
* file name functions: File Name Functions. (line 6)
* file name of makefile: Makefile Names. (line 6)
* file name of makefile, how to specify: Makefile Names. (line 30)
* file name prefix, adding: File Name Functions. (line 79)
* file name suffix: File Name Functions. (line 43)
* file name suffix, adding: File Name Functions. (line 68)
* file name with wildcards: Wildcards. (line 6)
* file name, abspath of: File Name Functions. (line 121)
* file name, basename of: File Name Functions. (line 57)
* file name, directory part: File Name Functions. (line 17)
* file name, nondirectory part: File Name Functions. (line 27)
* file name, realpath of: File Name Functions. (line 114)
* file, reading from: File Function. (line 6)
* file, writing to: File Function. (line 6)
* files, assuming new: Instead of Execution.
(line 38)
* files, assuming old: Avoiding Compilation.
(line 6)
* files, avoiding recompilation of: Avoiding Compilation.
(line 6)
* files, intermediate: Chained Rules. (line 16)
* filtering out words: Text Functions. (line 132)
* filtering words: Text Functions. (line 114)
* finding strings: Text Functions. (line 103)
* flags: Options Summary. (line 6)
* flags for compilers: Implicit Variables. (line 6)
* flavor of variable: Flavor Function. (line 6)
* flavors of variables: Flavors. (line 6)
* FORCE: Force Targets. (line 6)
* force targets: Force Targets. (line 6)
* Fortran, rule to compile: Catalogue of Rules. (line 49)
* functions: Functions. (line 6)
* functions, for controlling make: Make Control Functions.
(line 6)
* functions, for file names: File Name Functions. (line 6)
* functions, for text: Text Functions. (line 6)
* functions, syntax of: Syntax of Functions. (line 6)
* functions, user defined: Call Function. (line 6)
* g++ <1>: Implicit Variables. (line 49)
* g++: Catalogue of Rules. (line 39)
* gcc: Catalogue of Rules. (line 35)
* generating prerequisites automatically <1>: Automatic Prerequisites.
(line 6)
* generating prerequisites automatically: Include. (line 51)
* get <1>: Catalogue of Rules. (line 173)
* get: Implicit Variables. (line 69)
* globbing (wildcards): Wildcards. (line 6)
* goal: How Make Works. (line 11)
* goal, default <1>: How Make Works. (line 11)
* goal, default: Rules. (line 11)
* goal, how to specify: Goals. (line 6)
* grouped targets: Multiple Targets. (line 61)
* Guile <1>: Guile Integration. (line 6)
* Guile: Guile Function. (line 6)
* Guile example: Guile Example. (line 6)
* guile, conversion of types: Guile Types. (line 6)
* home directory: Wildcards. (line 11)
* IEEE Standard 1003.2: Overview. (line 13)
* ifdef, expansion: Reading Makefiles. (line 83)
* ifeq, expansion: Reading Makefiles. (line 83)
* ifndef, expansion: Reading Makefiles. (line 83)
* ifneq, expansion: Reading Makefiles. (line 83)
* implicit rule: Implicit Rules. (line 6)
* implicit rule, and directory search: Implicit/Search. (line 6)
* implicit rule, and VPATH: Implicit/Search. (line 6)
* implicit rule, definition of: Makefile Contents. (line 16)
* implicit rule, expansion: Reading Makefiles. (line 93)
* implicit rule, how to use: Using Implicit. (line 6)
* implicit rule, introduction to: make Deduces. (line 6)
* implicit rule, predefined: Catalogue of Rules. (line 6)
* implicit rule, search algorithm: Implicit Rule Search.
(line 6)
* implicit rules, secondary expansion of: Secondary Expansion.
(line 145)
* included makefiles, default directories: Include. (line 53)
* including (MAKEFILE_LIST variable): Special Variables. (line 8)
* including (MAKEFILES variable): MAKEFILES Variable. (line 6)
* including other makefiles: Include. (line 6)
* incompatibilities: Missing. (line 6)
* independent targets: Multiple Targets. (line 14)
* Info, rule to format: Catalogue of Rules. (line 158)
* inheritance, suppressing: Suppressing Inheritance.
(line 6)
* input during parallel execution: Parallel Input. (line 6)
* install (standard target): Goals. (line 92)
* installation directories, creating: Directory Variables. (line 20)
* installations, staged: DESTDIR. (line 6)
* interface for loaded objects: Loaded Object API. (line 6)
* intermediate files: Chained Rules. (line 16)
* intermediate files, preserving: Chained Rules. (line 46)
* intermediate targets, explicit: Special Targets. (line 44)
* interrupt: Interrupts. (line 6)
* job slots: Parallel. (line 6)
* job slots, and recursion: Options/Recursion. (line 25)
* job slots, sharing: Job Slots. (line 6)
* jobs, limiting based on load: Parallel. (line 35)
* jobserver: Job Slots. (line 16)
* jobserver on POSIX: POSIX Jobserver. (line 6)
* jobserver on Windows: Windows Jobserver. (line 6)
* joining lists of words: File Name Functions. (line 90)
* killing (interruption): Interrupts. (line 6)
* last-resort default rules: Last Resort. (line 6)
* ld: Catalogue of Rules. (line 86)
* lex <1>: Implicit Variables. (line 73)
* lex: Catalogue of Rules. (line 124)
* Lex, rule to run: Catalogue of Rules. (line 124)
* libraries for linking, directory search: Libraries/Search. (line 6)
* library archive, suffix rule for: Archive Suffix Rules.
(line 6)
* limiting jobs based on load: Parallel. (line 35)
* link libraries, and directory search: Libraries/Search. (line 6)
* link libraries, patterns matching: Libraries/Search. (line 6)
* linking, predefined rule for: Catalogue of Rules. (line 86)
* lint <1>: Implicit Variables. (line 80)
* lint: Catalogue of Rules. (line 146)
* lint, rule to run: Catalogue of Rules. (line 146)
* list of all prerequisites: Automatic Variables. (line 62)
* list of changed prerequisites: Automatic Variables. (line 52)
* load average: Parallel. (line 35)
* load directive: load Directive. (line 6)
* loaded object API: Loaded Object API. (line 6)
* loaded object example: Loaded Object Example.
(line 6)
* loaded object licensing: Loaded Object API. (line 32)
* loaded objects: Loading Objects. (line 6)
* loaded objects, remaking of: Remaking Loaded Objects.
(line 6)
* long lines, splitting: Splitting Lines. (line 6)
* loops in variable expansion: Flavors. (line 44)
* lpr (shell command) <1>: Wildcard Examples. (line 21)
* lpr (shell command): Empty Targets. (line 25)
* m2c <1>: Implicit Variables. (line 60)
* m2c: Catalogue of Rules. (line 74)
* macro: Using Variables. (line 10)
* make depend: Automatic Prerequisites.
(line 37)
* make extensions: Extending make. (line 6)
* make integration: Integrating make. (line 6)
* make interface to guile: Guile Interface. (line 6)
* make procedures in guile: Guile Interface. (line 6)
* makefile: Introduction. (line 7)
* makefile name: Makefile Names. (line 6)
* makefile name, how to specify: Makefile Names. (line 30)
* makefile rule parts: Rule Introduction. (line 6)
* makefile syntax, evaluating: Eval Function. (line 6)
* makefile, and MAKEFILES variable: MAKEFILES Variable. (line 6)
* makefile, conventions for: Makefile Conventions.
(line 6)
* makefile, how make processes: How Make Works. (line 6)
* makefile, how to write: Makefiles. (line 6)
* makefile, including: Include. (line 6)
* makefile, overriding: Overriding Makefiles.
(line 6)
* makefile, reading: Reading Makefiles. (line 6)
* makefile, remaking of: Remaking Makefiles. (line 6)
* makefile, simple: Simple Makefile. (line 6)
* makefiles, and MAKEFILE_LIST variable: Special Variables. (line 8)
* makefiles, and special variables: Special Variables. (line 6)
* makefiles, parsing: Parsing Makefiles. (line 6)
* makeinfo <1>: Catalogue of Rules. (line 158)
* makeinfo: Implicit Variables. (line 84)
* match-anything rule: Match-Anything Rules.
(line 6)
* match-anything rule, used to override: Overriding Makefiles.
(line 12)
* missing features: Missing. (line 6)
* mistakes with wildcards: Wildcard Pitfall. (line 6)
* modified variable reference: Substitution Refs. (line 6)
* Modula-2, rule to compile: Catalogue of Rules. (line 74)
* mostlyclean (standard target): Goals. (line 78)
* multi-line variable definition: Multi-Line. (line 6)
* multiple rules for one target: Multiple Rules. (line 6)
* multiple rules for one target (::): Double-Colon. (line 6)
* multiple targets: Multiple Targets. (line 6)
* multiple targets, in pattern rule: Pattern Intro. (line 44)
* name of makefile: Makefile Names. (line 6)
* name of makefile, how to specify: Makefile Names. (line 30)
* nested variable reference: Computed Names. (line 6)
* newline, quoting, in makefile: Simple Makefile. (line 41)
* newline, quoting, in recipes: Splitting Recipe Lines.
(line 6)
* nondirectory part: File Name Functions. (line 27)
* normal prerequisites: Prerequisite Types. (line 6)
* OBJ: Variables Simplify. (line 20)
* obj: Variables Simplify. (line 20)
* OBJECTS: Variables Simplify. (line 20)
* objects: Variables Simplify. (line 14)
* objects, loaded: Loading Objects. (line 6)
* OBJS: Variables Simplify. (line 20)
* objs: Variables Simplify. (line 20)
* old-fashioned suffix rules: Suffix Rules. (line 6)
* options: Options Summary. (line 6)
* options, and recursion: Options/Recursion. (line 6)
* options, setting from environment: Options/Recursion. (line 81)
* options, setting in makefiles: Options/Recursion. (line 81)
* order of pattern rules: Pattern Match. (line 30)
* order-only prerequisites: Prerequisite Types. (line 6)
* origin of variable: Origin Function. (line 6)
* output during parallel execution <1>: Options Summary. (line 169)
* output during parallel execution: Parallel Output. (line 6)
* overriding makefiles: Overriding Makefiles.
(line 6)
* overriding variables with arguments: Overriding. (line 6)
* overriding with override: Override Directive. (line 6)
* parallel execution: Parallel. (line 6)
* parallel execution, and archive update: Archive Pitfalls. (line 6)
* parallel execution, input during: Parallel Input. (line 6)
* parallel execution, output during <1>: Parallel Output. (line 6)
* parallel execution, output during: Options Summary. (line 169)
* parallel execution, overriding: Special Targets. (line 129)
* parallel output to terminal: Terminal Output. (line 6)
* parsing makefiles: Parsing Makefiles. (line 6)
* parts of makefile rule: Rule Introduction. (line 6)
* Pascal, rule to compile: Catalogue of Rules. (line 45)
* pattern rule: Pattern Intro. (line 6)
* pattern rule, expansion: Reading Makefiles. (line 93)
* pattern rules, order of: Pattern Match. (line 30)
* pattern rules, static (not implicit): Static Pattern. (line 6)
* pattern rules, static, syntax of: Static Usage. (line 6)
* pattern-specific variables: Pattern-specific. (line 6)
* pc <1>: Catalogue of Rules. (line 45)
* pc: Implicit Variables. (line 63)
* phony targets: Phony Targets. (line 6)
* phony targets and recipe execution: Instead of Execution.
(line 71)
* pitfalls of wildcards: Wildcard Pitfall. (line 6)
* plugin_is_GPL_compatible: Loaded Object API. (line 32)
* portability: Features. (line 6)
* POSIX <1>: Overview. (line 13)
* POSIX: Options/Recursion. (line 60)
* POSIX-conforming mode, setting: Special Targets. (line 142)
* post-installation commands: Install Command Categories.
(line 6)
* pre-installation commands: Install Command Categories.
(line 6)
* precious targets: Special Targets. (line 29)
* predefined rules and variables, printing: Options Summary. (line 185)
* prefix, adding: File Name Functions. (line 79)
* prerequisite: Rules. (line 6)
* prerequisite pattern, implicit: Pattern Intro. (line 22)
* prerequisite pattern, static (not implicit): Static Usage. (line 30)
* prerequisite types: Prerequisite Types. (line 6)
* prerequisite, expansion: Reading Makefiles. (line 93)
* prerequisites: Rule Syntax. (line 48)
* prerequisites, and automatic variables: Automatic Variables.
(line 17)
* prerequisites, automatic generation <1>: Include. (line 51)
* prerequisites, automatic generation: Automatic Prerequisites.
(line 6)
* prerequisites, introduction to: Rule Introduction. (line 8)
* prerequisites, list of all: Automatic Variables. (line 62)
* prerequisites, list of changed: Automatic Variables. (line 52)
* prerequisites, normal: Prerequisite Types. (line 6)
* prerequisites, order-only: Prerequisite Types. (line 6)
* prerequisites, varying (static pattern): Static Pattern. (line 6)
* preserving intermediate files: Chained Rules. (line 46)
* preserving with .PRECIOUS <1>: Special Targets. (line 29)
* preserving with .PRECIOUS: Chained Rules. (line 56)
* preserving with .SECONDARY: Special Targets. (line 49)
* print (standard target): Goals. (line 97)
* print target <1>: Wildcard Examples. (line 21)
* print target: Empty Targets. (line 25)
* printing directories: -w Option. (line 6)
* printing messages: Make Control Functions.
(line 43)
* printing of recipes: Echoing. (line 6)
* printing user warnings: Make Control Functions.
(line 35)
* problems and bugs, reporting: Bugs. (line 6)
* problems with wildcards: Wildcard Pitfall. (line 6)
* processing a makefile: How Make Works. (line 6)
* question mode: Instead of Execution.
(line 30)
* quoting %, in patsubst: Text Functions. (line 26)
* quoting %, in static pattern: Static Usage. (line 37)
* quoting %, in vpath: Selective Search. (line 38)
* quoting newline, in makefile: Simple Makefile. (line 41)
* quoting newline, in recipes: Splitting Recipe Lines.
(line 6)
* Ratfor, rule to compile: Catalogue of Rules. (line 49)
* RCS, rule to extract from: Catalogue of Rules. (line 164)
* reading from a file: File Function. (line 6)
* reading makefiles: Reading Makefiles. (line 6)
* README: Makefile Names. (line 9)
* realclean (standard target): Goals. (line 85)
* realpath: File Name Functions. (line 114)
* recipe: Simple Makefile. (line 74)
* recipe execution, single invocation: Special Targets. (line 136)
* recipe lines, single shell: One Shell. (line 6)
* recipe syntax: Recipe Syntax. (line 6)
* recipe, execution: Execution. (line 6)
* recipes <1>: Recipes. (line 6)
* recipes: Rule Syntax. (line 26)
* recipes setting shell variables: Execution. (line 12)
* recipes, and directory search: Recipes/Search. (line 6)
* recipes, backslash (\) in: Splitting Recipe Lines.
(line 6)
* recipes, canned: Canned Recipes. (line 6)
* recipes, comments in: Recipe Syntax. (line 29)
* recipes, echoing: Echoing. (line 6)
* recipes, empty: Empty Recipes. (line 6)
* recipes, errors in: Errors. (line 6)
* recipes, execution in parallel: Parallel. (line 6)
* recipes, how to write: Recipes. (line 6)
* recipes, instead of executing: Instead of Execution.
(line 6)
* recipes, introduction to: Rule Introduction. (line 8)
* recipes, quoting newlines in: Splitting Recipe Lines.
(line 6)
* recipes, splitting: Splitting Recipe Lines.
(line 6)
* recipes, using variables in: Variables in Recipes.
(line 6)
* recompilation: Introduction. (line 22)
* recompilation, avoiding: Avoiding Compilation.
(line 6)
* recording events with empty targets: Empty Targets. (line 6)
* recursion: Recursion. (line 6)
* recursion, and -C: Options/Recursion. (line 22)
* recursion, and -f: Options/Recursion. (line 22)
* recursion, and -j: Options/Recursion. (line 25)
* recursion, and -o: Options/Recursion. (line 22)
* recursion, and -t: MAKE Variable. (line 34)
* recursion, and -W: Options/Recursion. (line 22)
* recursion, and -w: -w Option. (line 20)
* recursion, and command line variable definitions: Options/Recursion.
(line 17)
* recursion, and environment: Variables/Recursion. (line 6)
* recursion, and MAKE variable: MAKE Variable. (line 6)
* recursion, and MAKEFILES variable: MAKEFILES Variable. (line 15)
* recursion, and options: Options/Recursion. (line 6)
* recursion, and printing directories: -w Option. (line 6)
* recursion, and variables: Variables/Recursion. (line 6)
* recursion, level of: Variables/Recursion. (line 115)
* recursive variable expansion <1>: Using Variables. (line 6)
* recursive variable expansion: Flavors. (line 6)
* recursively expanded variables: Flavors. (line 6)
* reference to variables <1>: Reference. (line 6)
* reference to variables: Advanced. (line 6)
* relinking: How Make Works. (line 46)
* remaking loaded objects: Remaking Loaded Objects.
(line 6)
* remaking makefiles: Remaking Makefiles. (line 6)
* removal of target files <1>: Interrupts. (line 6)
* removal of target files: Errors. (line 63)
* removing duplicate words: Text Functions. (line 155)
* removing targets on failure: Special Targets. (line 64)
* removing whitespace from split lines: Splitting Lines. (line 40)
* removing, to clean up: Cleanup. (line 6)
* reporting bugs: Bugs. (line 6)
* rm: Implicit Variables. (line 106)
* rm (shell command) <1>: Errors. (line 27)
* rm (shell command) <2>: Wildcard Examples. (line 12)
* rm (shell command) <3>: Simple Makefile. (line 85)
* rm (shell command): Phony Targets. (line 20)
* rule prerequisites: Rule Syntax. (line 48)
* rule syntax: Rule Syntax. (line 6)
* rule targets: Rule Syntax. (line 18)
* rule, double-colon (::): Double-Colon. (line 6)
* rule, explicit, definition of: Makefile Contents. (line 10)
* rule, how to write: Rules. (line 6)
* rule, implicit: Implicit Rules. (line 6)
* rule, implicit, and directory search: Implicit/Search. (line 6)
* rule, implicit, and VPATH: Implicit/Search. (line 6)
* rule, implicit, chains of: Chained Rules. (line 6)
* rule, implicit, definition of: Makefile Contents. (line 16)
* rule, implicit, how to use: Using Implicit. (line 6)
* rule, implicit, introduction to: make Deduces. (line 6)
* rule, implicit, predefined: Catalogue of Rules. (line 6)
* rule, introduction to: Rule Introduction. (line 6)
* rule, multiple for one target: Multiple Rules. (line 6)
* rule, no recipe or prerequisites: Force Targets. (line 6)
* rule, pattern: Pattern Intro. (line 6)
* rule, static pattern: Static Pattern. (line 6)
* rule, static pattern versus implicit: Static versus Implicit.
(line 6)
* rule, with multiple targets: Multiple Targets. (line 6)
* rules, and $: Rule Syntax. (line 34)
* s. (SCCS file prefix): Catalogue of Rules. (line 173)
* SCCS, rule to extract from: Catalogue of Rules. (line 173)
* search algorithm, implicit rule: Implicit Rule Search.
(line 6)
* search path for prerequisites (VPATH): Directory Search. (line 6)
* search path for prerequisites (VPATH), and implicit rules: Implicit/Search.
(line 6)
* search path for prerequisites (VPATH), and link libraries: Libraries/Search.
(line 6)
* searching for strings: Text Functions. (line 103)
* secondary expansion: Secondary Expansion. (line 6)
* secondary expansion and explicit rules: Secondary Expansion.
(line 105)
* secondary expansion and implicit rules: Secondary Expansion.
(line 145)
* secondary expansion and static pattern rules: Secondary Expansion.
(line 137)
* secondary files: Chained Rules. (line 46)
* secondary targets: Special Targets. (line 49)
* sed (shell command): Automatic Prerequisites.
(line 73)
* selecting a word: Text Functions. (line 159)
* selecting word lists: Text Functions. (line 168)
* sequences of commands: Canned Recipes. (line 6)
* setting options from environment: Options/Recursion. (line 81)
* setting options in makefiles: Options/Recursion. (line 81)
* setting variables: Setting. (line 6)
* several rules for one target: Multiple Rules. (line 6)
* several targets in a rule: Multiple Targets. (line 6)
* shar (standard target): Goals. (line 103)
* shell command, function for: Shell Function. (line 6)
* shell file name pattern (in include): Include. (line 13)
* shell variables, setting in recipes: Execution. (line 12)
* shell wildcards (in include): Include. (line 13)
* shell, choosing the: Choosing the Shell. (line 6)
* SHELL, exported value: Variables/Recursion. (line 23)
* SHELL, import from environment: Environment. (line 37)
* shell, in DOS and Windows: Choosing the Shell. (line 38)
* SHELL, MS-DOS specifics: Choosing the Shell. (line 44)
* SHELL, value of: Choosing the Shell. (line 6)
* signal: Interrupts. (line 6)
* silent operation: Echoing. (line 6)
* simple makefile: Simple Makefile. (line 6)
* simple variable expansion: Using Variables. (line 6)
* simplifying with variables: Variables Simplify. (line 6)
* simply expanded variables: Flavors. (line 56)
* sorting words: Text Functions. (line 146)
* spaces, in variable values: Flavors. (line 107)
* spaces, stripping: Text Functions. (line 80)
* special targets: Special Targets. (line 6)
* special variables: Special Variables. (line 6)
* specifying makefile name: Makefile Names. (line 30)
* splitting long lines: Splitting Lines. (line 6)
* splitting recipes: Splitting Recipe Lines.
(line 6)
* staged installs: DESTDIR. (line 6)
* standard input: Parallel Input. (line 6)
* standards conformance: Overview. (line 13)
* standards for makefiles: Makefile Conventions.
(line 6)
* static pattern rule: Static Pattern. (line 6)
* static pattern rule, syntax of: Static Usage. (line 6)
* static pattern rule, versus implicit: Static versus Implicit.
(line 6)
* static pattern rules, secondary expansion of: Secondary Expansion.
(line 137)
* stem <1>: Pattern Match. (line 6)
* stem: Static Usage. (line 17)
* stem, shortest: Pattern Match. (line 38)
* stem, variable for: Automatic Variables. (line 78)
* stopping make: Make Control Functions.
(line 11)
* strings, searching for: Text Functions. (line 103)
* stripping whitespace: Text Functions. (line 80)
* sub-make: Variables/Recursion. (line 6)
* subdirectories, recursion for: Recursion. (line 6)
* substitution variable reference: Substitution Refs. (line 6)
* suffix rule: Suffix Rules. (line 6)
* suffix rule, for archive: Archive Suffix Rules.
(line 6)
* suffix, adding: File Name Functions. (line 68)
* suffix, function to find: File Name Functions. (line 43)
* suffix, substituting in variables: Substitution Refs. (line 6)
* suppressing inheritance: Suppressing Inheritance.
(line 6)
* switches: Options Summary. (line 6)
* symbol directories, updating archive: Archive Symbols. (line 6)
* syntax of recipe: Recipe Syntax. (line 6)
* syntax of rules: Rule Syntax. (line 6)
* tab character (in commands): Rule Syntax. (line 26)
* tabs in rules: Rule Introduction. (line 21)
* TAGS (standard target): Goals. (line 111)
* tangle <1>: Catalogue of Rules. (line 151)
* tangle: Implicit Variables. (line 100)
* tar (standard target): Goals. (line 100)
* target: Rules. (line 6)
* target pattern, implicit: Pattern Intro. (line 9)
* target pattern, static (not implicit): Static Usage. (line 17)
* target, deleting on error: Errors. (line 63)
* target, deleting on interrupt: Interrupts. (line 6)
* target, expansion: Reading Makefiles. (line 93)
* target, multiple in pattern rule: Pattern Intro. (line 44)
* target, multiple rules for one: Multiple Rules. (line 6)
* target, touching: Instead of Execution.
(line 23)
* target-specific variables: Target-specific. (line 6)
* targets: Rule Syntax. (line 18)
* targets without a file: Phony Targets. (line 6)
* targets, built-in special: Special Targets. (line 6)
* targets, empty: Empty Targets. (line 6)
* targets, force: Force Targets. (line 6)
* targets, grouped: Multiple Targets. (line 61)
* targets, independent: Multiple Targets. (line 14)
* targets, introduction to: Rule Introduction. (line 8)
* targets, multiple: Multiple Targets. (line 6)
* targets, phony: Phony Targets. (line 6)
* terminal rule: Match-Anything Rules.
(line 6)
* terminal, output to: Terminal Output. (line 6)
* test (standard target): Goals. (line 115)
* testing compilation: Testing. (line 6)
* tex <1>: Implicit Variables. (line 87)
* tex: Catalogue of Rules. (line 151)
* TeX, rule to run: Catalogue of Rules. (line 151)
* texi2dvi <1>: Implicit Variables. (line 91)
* texi2dvi: Catalogue of Rules. (line 158)
* Texinfo, rule to format: Catalogue of Rules. (line 158)
* tilde (~): Wildcards. (line 11)
* tools, sharing job slots: Job Slots. (line 6)
* touch (shell command) <1>: Empty Targets. (line 25)
* touch (shell command): Wildcard Examples. (line 21)
* touching files: Instead of Execution.
(line 23)
* traditional directory search (GPATH): Search Algorithm. (line 42)
* types of prerequisites: Prerequisite Types. (line 6)
* types, conversion of: Guile Types. (line 6)
* undefined variables, warning message: Options Summary. (line 287)
* undefining variable: Undefine Directive. (line 6)
* updating archive symbol directories: Archive Symbols. (line 6)
* updating loaded objects: Remaking Loaded Objects.
(line 6)
* updating makefiles: Remaking Makefiles. (line 6)
* user defined functions: Call Function. (line 6)
* value: Using Variables. (line 6)
* value, how a variable gets it: Values. (line 6)
* variable: Using Variables. (line 6)
* variable definition: Makefile Contents. (line 22)
* variable references in recipes: Variables in Recipes.
(line 6)
* variables: Variables Simplify. (line 6)
* variables, $ in name: Computed Names. (line 6)
* variables, and implicit rule: Automatic Variables. (line 6)
* variables, appending to: Appending. (line 6)
* variables, automatic: Automatic Variables. (line 6)
* variables, command line: Overriding. (line 6)
* variables, command line, and recursion: Options/Recursion. (line 17)
* variables, computed names: Computed Names. (line 6)
* variables, conditional assignment: Flavors. (line 133)
* variables, defining verbatim: Multi-Line. (line 6)
* variables, environment <1>: Environment. (line 6)
* variables, environment: Variables/Recursion. (line 6)
* variables, exporting: Variables/Recursion. (line 6)
* variables, flavor of: Flavor Function. (line 6)
* variables, flavors: Flavors. (line 6)
* variables, how they get their values: Values. (line 6)
* variables, how to reference: Reference. (line 6)
* variables, loops in expansion: Flavors. (line 44)
* variables, modified reference: Substitution Refs. (line 6)
* variables, multi-line: Multi-Line. (line 6)
* variables, nested references: Computed Names. (line 6)
* variables, origin of: Origin Function. (line 6)
* variables, overriding: Override Directive. (line 6)
* variables, overriding with arguments: Overriding. (line 6)
* variables, pattern-specific: Pattern-specific. (line 6)
* variables, recursively expanded: Flavors. (line 6)
* variables, setting: Setting. (line 6)
* variables, simply expanded: Flavors. (line 56)
* variables, spaces in values: Flavors. (line 107)
* variables, substituting suffix in: Substitution Refs. (line 6)
* variables, substitution reference: Substitution Refs. (line 6)
* variables, target-specific: Target-specific. (line 6)
* variables, unexpanded value: Value Function. (line 6)
* variables, warning for undefined: Options Summary. (line 287)
* varying prerequisites: Static Pattern. (line 6)
* verbatim variable definition: Multi-Line. (line 6)
* vpath: Directory Search. (line 6)
* VPATH, and implicit rules: Implicit/Search. (line 6)
* VPATH, and link libraries: Libraries/Search. (line 6)
* warnings, printing: Make Control Functions.
(line 35)
* weave <1>: Catalogue of Rules. (line 151)
* weave: Implicit Variables. (line 94)
* Web, rule to run: Catalogue of Rules. (line 151)
* what if: Instead of Execution.
(line 38)
* whitespace, avoiding on line split: Splitting Lines. (line 40)
* whitespace, in variable values: Flavors. (line 107)
* whitespace, stripping: Text Functions. (line 80)
* wildcard: Wildcards. (line 6)
* wildcard pitfalls: Wildcard Pitfall. (line 6)
* wildcard, function: File Name Functions. (line 107)
* wildcard, in archive member: Archive Members. (line 36)
* wildcard, in include: Include. (line 13)
* wildcards and MS-DOS/MS-Windows backslashes: Wildcard Pitfall.
(line 31)
* Windows, choosing a shell in: Choosing the Shell. (line 38)
* word, selecting a: Text Functions. (line 159)
* words, extracting first: Text Functions. (line 184)
* words, extracting last: Text Functions. (line 197)
* words, filtering: Text Functions. (line 114)
* words, filtering out: Text Functions. (line 132)
* words, finding number: Text Functions. (line 180)
* words, iterating over: Foreach Function. (line 6)
* words, joining lists: File Name Functions. (line 90)
* words, removing duplicates: Text Functions. (line 155)
* words, selecting lists of: Text Functions. (line 168)
* writing recipes: Recipes. (line 6)
* writing rules: Rules. (line 6)
* writing to a file: File Function. (line 6)
* yacc <1>: Implicit Variables. (line 77)
* yacc <2>: Catalogue of Rules. (line 120)
* yacc: Canned Recipes. (line 18)
* Yacc, rule to run: Catalogue of Rules. (line 120)
* ~ (tilde): Wildcards. (line 11)